What do you use to make tzatziki? Onions, garlic, or both? I found tzatziki sauce in a supermarket. If I recall correctly, the ingredients listed on the package included onions. I then read on Internet that tzatziki sauce is made with garlic.  

What do you use to make tzatziki, onions, garlic, or both?
Typically garlic is used.  If you prefer onions and garlic, go ahead but it's typically cucumber, yogurt, dill, garlic, lemon juice or vinegar, olive oil, salt, pepper, and sometimes sour cream.