I believe that you are referring to a “slow carbohydrate” as a carbohydrate that takes longer for the body to digest. These are referred to as complex carbohydrates. The carbohydrates consist of whole grain products and beans. “Fast carbohydrates” are more quickly digested by the body and are known as simple carbohydrates. Onions are not placed into either of these categories (simple or complex carbohydrates). Try our Lime Marinated Onion Salad.