Soup vegetable is a term used to describe vegetables that are commonly used in soups. The three most common soup vegetables are OKRA (4 letters), PEA (3 letters) and LEEK (4 letters). OKRA is a green, pod-like vegetable that is often used in gumbo and other soups. Peas are small, round vegetables that are usually green or yellow in color and are often used in split PEA soup. Leeks are a type of onion that have a mild flavor and are often used in French onion soup.