Sometimes a recipe calls for cooking vegetables at different times, "Sauté garlic for two minutes, add onions and sauté for five minutes. Add carrots, blah blah blah". So instead of dirtying two or three or five bowls, I layer my ingredients. The ingredient to be cooked last is on the bottom; separate the next layer with plastic wrap and keep making layers of ingredients. You'll have to read the entire recipe from start to finish to know what goes to the bottom but once you do, you won't have a gajillion bowls to wash later.