An onion is a round vegetable with a brown skin that grows underground. It has many white layers on its inside which have a strong, sharp smell and taste. .. It is made with fresh minced meat, cooked with onion and a rich tomato sauce. Key Feature: Packed With Nutrients. Onions are nutrient-dense, meaning they're low in calories but high in vitamins and minerals. .. May Benefit Heart Health. .. Loaded With Antioxidants. .. Contain Cancer-Fighting Compounds. .. Help Control Blood Sugar. .. May Boost Bone Density. .. Have Antibacterial Properties. .. May Boost Digestive� Health.