01 - In a mixing bowl, combine ground turkey, red onion, garlic, Worcestershire sauce, smoked paprika, salt, and black pepper. Mix gently until just combined.
02 - Divide the mixture into 4 equal portions and shape into patties approximately 1/2 inch thick.
03 - Preheat grill or skillet to medium-high heat and lightly oil the cooking surface.
04 - Cook patties for 5 to 6 minutes on each side, or until the internal temperature reaches 165°F.
05 - Place a slice of Swiss cheese on each patty during the last minute of cooking and cover to melt.
06 - Toast the burger buns cut side down until lightly golden.
07 - Spread mayonnaise or Greek yogurt and Dijon mustard on the bottom buns if desired. Layer with lettuce, turkey patty with melted cheese, sliced avocado, tomato, and sprouts. Top with the upper bun.
08 - Serve immediately for best freshness and flavor.