Preheat an indoor or outdoor grill to medium, medium-high. Place the first 7 ingredients in a bowl and mix until just combined. Shape into 4 patties each about 3/4-inch thick. Cook the burgers for about 4 minutes per side, or until entirely cooked through and the centre of the burger reaches 160 degrees F (71 degrees C) on an instant read meat thermometer. Cut and spread the buns with the low-fat mayonnaise. Top the bottom buns with the lettuce and red onion. Set on the burgers, top with the tomatoes, cucumber, sprouts or shoots and top buns, and then serve.
Options: Top the burger with a slice of cheddar, Swiss or mozzarella cheese, allowing it to melt before removing the burger from the grill. Sauté or grill the red onion if you prefer your onions cooked. Top the burger with other toppings that appeal, such as sautéed mushrooms or pickles.