Preheat a griddle, skillet or grill to medium heat.
In a large mixing bowl, mix together ground turkey, eggs, bread crumbs, minced garlic, 2 Tablespoons teriyaki sauce, salt and pepper until well combined. Divide turkey mixture evenly into 6 patties (approximately 6.7 ounces each).
Spray griddle or skillet generously with nonstick cooking spray (or lightly oil grill grates). Grill the burgers for 5-6 minutes on each side, or until cooked through and they reach an internal temperature of 165 degrees F.
Brush 1 teaspoon of teriyaki sauce on each burger after flipping. Remove burgers from heat and set aside.
Place pineapple slices over heat and grill on each side for 1-2 minutes or until heated through.
Place each burger on 2 lettuce leaves, top with a grilled pineapple ring and 2 onion slices. Serve on a bun, if desired (not included in nutrition information).