Where does the tangy flavor come from? Not from the chick peas!
Probably vinegar [something artsy and artisanal, no doubt] or lime or lemon.
:)
If you don’t use enough tahini (basically pureed toasted sesame seeds), it’s not going to taste like hummus. There’s a little garlic, maybe some lemon juice, maybe some olive oil, but the flavor is pretty much the garbanzo beans and tahini.