Risa

It's inspired by the Priestly Blessing but the latter requires two hands, so saying that the vulcan salute is itself a "Jewish symbol" is not really accurate.

Interestingly, according to the this comment, the first use of it on Star Trek was not by Spock but rather by T'Pau - who was played by Celia Lovsky, who happens to have been previously married to Peter Lorre.