The term 'Veggieburger Ingredient' can be summarized by two crossword solutions: SOY (3 letters) and SOYBEAN (7 letters). SOY is a type of legume that is widely used in many cuisines around the world. It is a popular ingredient in vegetarian dishes, such as veggieburgers, due to its high protein content and meat-like texture. Soybeans are the edible seed of the SOY plant, and are often used to make SOY milk, tofu, and other products. They are also a key ingredient in many veggieburgers, providing a nutty flavor and a hearty texture.