There are recipes that use mayonnaise and olive oil, but I wanted to try making something without oil.

If you let it sit for a day, the spiciness of the garlic with get a bit more mild.
You can use lemon juice instead of vinegar.
Adjust the amount of salt and pepper to taste (I use powdered salt to make it easier to dissolve).
If you use low-fat yogurt, there's even fewer calories. Recipe by fuwari1