Turkish or Greek yogurt, preferably of thinner, pourable consistency
Stir the yogurt smooth in a bowl and stir in tahini and oil a little at a time. Season with lemon juice (adding pressed or grated garlic to taste, if you like).
Dilute the sauce, if necessary, by stirring in water a little at a time. Serve the sauce with various meat or fish dishes (like kebab pita breads), or mix with grilled or oven-baked vegetables, like aubergines.
Recipe source: adapted from "Roast aubergines with tahini" by food writer Nigel Slater/Observer Food Monthly, January/2005.