The term 'burger garnish' refers to the condiments and toppings that are added to a hamburger to enhance its flavor. Common garnishes for burgers include ONION and KETCHUP, which both have five and seven letters respectively. ONION is a vegetable that is often sliced and added to burgers for a sweet and savory flavor. KETCHUP is a condiment made from tomatoes, vinegar, sugar, and spices, and is often used as a topping for burgers.