Sooner or later, every cook runs into a situation where the exact ingredient isn't on hand. In many cases, emergency substitutions can be made that will save both the recipe and the day. Need a cup of buttermilk? Try using a cup of yogurt, instead. If you don't have orange liqueur available, substitute an equal amount of frozen orange juice concentrate. You can mince the tops of green onions and use them in recipes that call for chives, or use celery tops instead of parsley. Hardly anyone has veal stock handy, but a half-and-half mixture of beef and chicken stocks gives similar results. While it's always best to use fresh ingredients when possible, it's a good idea to keep dried and powdered ingredients handy for emergency use. An eighth of a teaspoon of garlic powder equals a small clove. A small onion equates to a teaspoon of onion powder or a tablespoon of the dried version. Many general-purpose cookbooks will include a section on ingredients that can substituted in a pinch.