Combine mayonnaise and mustard in a small bowl to make the burger sauce.

In a separate bowl, combine ground turkey, shredded zucchini, minced fresh cilantro, low-sodium soy sauce, and coarsely ground black pepper.

Divide the turkey mixture into 4 equal portions.

Shape each portion into a 1/4-inch-thick patty.

Heat a large nonstick skillet coated with cooking spray over medium-high heat.

Add the turkey patties to the skillet.

Cook for 4 minutes on one side.

Turn the patties over and cook for 3 minutes or until cooked through.

Top each patty with two slices of reduced-fat Cheddar cheese.

Cover the skillet and cook for 1 minute, or until the cheese is melted.

Spread 1 1/2 teaspoons of the mayonnaise mixture over the cut side of each of the 4 muffin halves.

Top each of the bottom muffin halves with a cooked turkey patty, a large green leaf lettuce leaf, and the muffin top.