In the mixing bowl, combine the ground turkey, breadcrumbs, chopped onions, bell peppers, minced garlic, egg, Worcestershire sauce, salt, and black pepper. Mix well until all the ingredients are evenly distributed.
Divide the mixture into four equal portions and shape them into burger patties. Remember, the patties will shrink slightly during cooking, so make them a bit larger than the bun size.
Preheat your grill or stovetop skillet over medium heat. Lightly oil the cooking surface to prevent sticking.
Place the turkey patties on the grill or skillet and cook for about 5-6 minutes on each side, or until they are fully cooked and have an internal temperature of 165°F (75°C).
Toast the whole wheat burger buns on the grill or in a toaster until they're slightly crispy.
Assemble your turkey burgers by placing a lettuce leaf on the bottom bun, followed by a turkey patty, tomato slices, and any other toppings you desire. Top it off with the other half of the bun.