Garlic flakes are small, dehydrated pieces of garlic. You use garlic flakes in liquid dishes that undergo some cooking time, to soften the pieces and let them release the garlic flavour. Typical dishes in which they are used include soups, stews, sauces, meat loaves, and casseroles. Garlic flakes don't work in items such as an oil and vinegar salad dressing: a dressing has the liquid, but doesn't have the cooking.