I don't know if this is the type of thing you were asking, but it's one I've been using about once a week lately.

I was listening to How I Built This with Guy Raz, and he had on a lady that wanted to eliminate food waste. She started the app Too Good To Go.

Partner businesses will pack up about $15 of food at the end of the shift, and instead of tossing it, they put it in a to go box for you for $5.

Tonight we had jerk chicken and sides from a Caribbean place, another time we got 4 big pizza slices overloaded with toppings, and our favorite is the Manhattan Bagels gives us 15-17 bagels. We've also tried a vegan bakery, which is way too expensive for us, but for my girlfriend's nephew with a severe egg allergy was a great surprise.

These are all places we wouldn't normally go, but they've all been really tasty, helped eliminate some waste, and let us try some new restaurants for a fiver. We're kinda in the country, so there aren't too many options, but I looked in the nearby city and there are a lot, and the app started in Europe, so you non-US people don't have to miss out.

So maybe not the super cheap lentil curry recipe I have, but this was an intriguing things I recently learned about and have been looking to share awareness about.

Even if you don't have much cash, it still feels nice to be able to get restaurant food sometimes too, and this is a cheap and mutually beneficial way to do that.

Sous vide cooking. It's easy to buy a bulk quantity of food, vac-pack and cook it, then freeze it. This saves time and money both on purchase, initial prep, and mealtime prep.

For example, we buy a whole, locally-grown, grass-fed chuck flap. We trim, bag, and cook the entire flap in one day. This provides my partner and me about six weeks of meals with high quality protein. Added bonus: the juice and gelatin in the bag after cooking makes excellent soup stock or cooking liquid for beans. Double added bonus: a sous vide chuck steak is just as good as the best ribeye fillet.

Also learn to use an entire chicken. For example, spatchcock and roast the chicken for dinner. Break down the carcass to get every scrap of meat. Make chicken salad the next day. Roast the bones, make a mirepoix, and make chicken stock. Use that to make chicken and dumplings or chicken soup. The two of us eat for a week from one chicken.

Learn about food preservation and safety: reusable containers, dangerous food conditions, fermentation, canning, making stocks... A huge part of saving money on food is not wasting any of it. Being able to buy in-season food when it's cheaper and more nutritive is a big deal.

And on that note: avoid cheap, low-nutrition food. Sure, that industrial, NPK produce and ultra-processed box meal might be "affordable." But those tend to be empty calories; you have to eat more of it to feel sated and get the nutrition you need. Locally grown, in-season foods tend to be better food values since you need to eat less of them to get the same micronutrients. See: "The Doritos Effect," by Mark Schatzker.

Meal planning carefully to take advantage of sales, buy in bulk when possible, and eliminate food waste. I have my meals planned out through the end of January and I do this every month. The money I spend on groceries has halved since I started using this approach.

When you order pizza, ask for extra sauce, not cheese. They typically don't charge for that but often include extra toppings to make the pizza look "normal"

One thing I've realised after many years of trying to eat cheap and healthy is that not all cheap and healthy food advice applies in every region - you really need local advice to make the best choices possible.

For example, I've often read the advice to eat rice to stay cheap, but where I live, potatoes usually come out to be cheaper, especially just after harvesting. Potatoes are also arguably a better choice from a health perspective.

If you're one of the people who like the bowls from fast casual places like Chipotle, Qdoba, or even those poke bowl places, get their non-protein/vegetarian option then go home and add your own protein. This saves about $2-$4 a bowl and can possibly extend the bowl's lifespan into two meals.

I bring it home my bowl and add in my own falafel, chicken, shrimp, or whatever protein I have on hand. Getting frozen protein and airfrying it is the easiest. I guess I could also grill stuff but I'm usually short on time.

The highest rated recipe on BBC Good Food is Chilli con Carne. It's cheap and easy to make, and can be dumped on top of a big pile of rice

https://www.bbcgoodfood.com/recipes/chilli-con-carne-recipe

Cabbages, dried beans/peas/lentils, and collards. Learn to cook these "poor foods" in ways you like - they are cheap and plentiful and amenable to lots of different methods (cabbage, especially). Extend/bulk all the above with rice, farro, polenta, tortillas, or a solid southern cornbread recipe (not sweet and more cornmeal than flour).

I do both collards and beans in an instant pot (not together, though), which cuts down on mess and time. One of my favorite things to do with cabbage is make Kim chi or sauerkraut. Kraut is easier (and a little cheaper, it's just cabbage, salt, and time) and opens up a realm of easy Euro-ish meals (kraut, lentils/potatoes, and sausages, for example, is highly economical, tasty, and filling).

You can substitute ~75% of your meals volume with rice and come out just a satisfied with a fraction of the cost.

Get a rice cooker with a steam tray. Make a cup of rice, with frozen veggies in the tray. Spice the rice if you want (a little cumin with pepper slices makes excellent fajitas).

When I was in college I put rice in everything because it disgusted my flatmates. I could cook a meal and repel mooches at the same time.

Don't tell anyone this, but the ducks in the park are free, you can take as many of them as you want

Instant pot. Throw your leftovers or whatever into it and press the button. Cook beans from dry to tender in less than an hour. Dump bag of Trader Joe frozen kung pao chicken (all the little inner bags of ingredients) and cook for 4 minutes, etc. Better than a microwave, really. You can actually cook stuff in it.

1 cup of lentils, can tomatoes, carrots, celery, onions, 5 to 6 cups of water, 1 tsp salt. From there season with whatever. Want an Italian taste add oregano, basil, etc. Want more Indian add curry powder, cumin, ginger. It really takes on the flavor profile of whatever you add to it. Inexpensive and very healthy.

Dr Pepper and Cold Brew make a fantastic mixed drink; it tastes similar to spiced rum with no alcohol.

If you buy milk alternatives regularly it might be worth getting a high powered blender and a nut milk bag and making your own nut milk. Any high powered (2200W) blender will work, you don't need a $500 Vitamix, there are some brands for around $100 on Amazon- CasaCosa is a good one. But a regular or compact blender will not work.

There are shockingly few nuts in a half gallon of almond milk and it takes like 5 minutes including clean up. It only lasts about 4 days in the fridge, so it's twice a week kind of thing, but it's really not difficult. If you use cashews you don't even have to strain it, since they have very little fiber.

If you do use a high fiber nut, like almonds or walnuts, you can save the pulp and use it instead of (or in addition to) regular flour to make quick breads (pumpkin, banana, zucchini, etc.) and pancakes.

Soak dried Porcini or Shiitake mushroom in a bowl of warm water for about 20 min (can boil the mushrooms if fresh). The mushrooms then can be used as an ingredient to a variety of recipes but more importantly, the bowl of water is now an umami bomb, and can be used as a broth or seasoning to add a ton of flavor to a bunch of dishes (pasta sauce, soup, stir-fry...)

Porcini in particular has an earthly, nutty taste and can be used to create complex sauces with a "beefy" taste.

Crock Pot, skinless chicken thighs, bottled sauce of your choice, frozen veggies of your choice, cook until chicken is done.

Chicken thighs are the cheapest chicken meat and changing up the flavor of sauce and blend of veggies makes it feel like completely different meals.

Serve over rice or pasta, depending on which kind of sauce you used.

Lots of beans and rice. So many different meals with beans and rice.

A garden. Or knowing someone with a garden, at some point we all get an excess of something, I gave a big bag of jalapenos to our yard guys at the end of the summer, they were so abundant.

We do use the Too Good to Go app, but not many participating restaurants here, it's more for a treat.

Working at a restaurant that feeds you, I used to work at a place you could come for supper (teatime) before the evening shift. Not a chain place.

Set aside some part of the weekly budget for oil, spices, seasonings, chili paste, condiments. With these you can build variety of flavor into a basic cheap diet and they last awhile, you don't have to buy all of them each time, but always buy some.

ETA: planning the week of meals saves more money than trying to buy cheap foods, for me, but we still have kids at home so the calculation is a little different. I just don't like to - so I make a loose framework, know about 4 of the 7 meals, and keep dry/canned beans and pasta and rice on hand, and there is usually some veg in the garden, so I can leave some room for improvisation. Even that level of planning does save money.

Box of saltine crackers and Betty Crocker chocolate frosting, just a few will do ya.  

Easy (relatively) chowder with random veg, protein and cheese

The only specific ingredients are onions, garlic, spices, heavy cream and at least some cheddar.

Before starting salt all of your veg. This is so they are INTERNALLY seasoned, otherwise you'll have salty soup and bland veg.

Saute your onions (with any other hardy vegetables) and butter can be used if feeling indulgent. Salt as you saute

Once slightly tender add and cook a couple tablespoons of flour (depends on quantity of soup and desired thickness)

Add whatever stock or bullion on hand (I use home made with bones and veg scraps). You could also use plain water if really starving and desperate though.

Once the soup is boiling add a ton of (salted) minced garlic, FRESH CRACKED black pepper, rosemary, thyme, smoked paprika and a couple pinches of mustard powder. These can be fresh or dry, but I do like fresh garlic and fresh cracked pepper (many of the flavors and compounds are highly volatile and will literally float away if stored post cracking). Also be generous with your spices, makes it way tastier.

Add your veg. It can really be anything from broccoli, cauliflower, potatoes, corn, peas, carrots, mushrooms zucchini, celery, cabbage (not too much), bell peppers, etc. experiment and go nuts.

When pot is hot again add your protein, nothing specific. I've used ham, pork, ground beef, ground turkey, deli meat that was gonna go bad, breakfast sausages, Italian sausages, chicken breast and thighs and even tilapia. Make sure to salt them for 15 mins before adding.

When your proteins are not raw and almost cooked add heavy cream (if you don't have much you can also add some milk, you can also freeze milk, let it melt and drip into a container, when halfway melted remove the frozen milk and whatever is collected is highly concentrated because all of the fats in the milk melt much faster than water)

When soup is reduced to desired amount turn off the heat and let it cool to a light simmer. Add your cheese and stir thoroughly. If soup is too hot your cheese will cook and clump up in nasty globs and will not thicken your soup either.

Flour is the highest nutrients per dollar you can buy. Make some bachelor cookies!

If you are forced to consuming mostly cheap packaged goods like Hamburger Helper and the like, add the secret spice blend to make it actually have some flavor:

Salt*, pepper, onion powder, garlic powder and MSG.

*Check the sodium levels already in the packaged food first; if it's already high, you can ignore adding more.

These spices are cheap and make everything so much better. Even non-savory stuff sometimes benefits.