For many people, onions cause heartburn or other digestive discomfort. If onions interfere with your enjoyment of a meal, or if you don't have one when preparing a recipe that calls for it, onion powder works as a substitute. A pinch of onion powder also works in a pinch if you don't have time to peel and chop an onion. Keep in mind, though, that onion powder, which is pulverized dried onion, lacks much of the nutritional benefits of whole fresh onion, and it doesn't add texture or as fresh a flavor.
Use onion powder in place of onion in any instance. If the flavor of whole, fresh onion complements a food, onion powder does as well.
Substitute 1 tsp. of onion powder per every small onion or 1/3 cup of chopped onion a recipe calls for. Replace 1 tbsp. of dried onion flakes with 1 tsp. of onion powder.
Add onion powder to food during the final 15 minutes of cooking, even when a recipe calls for onion to be included earlier on.
Pour onion powder into your hand first when adding it to a pot or pan. Dump it in from your hand, rather than from the container, to avoid letting steam into the container.