Toast mustard seeds in a skillet over low heat until they pop.

Transfer toasted mustard seeds to a bowl.

Combine applesauce, 1 tablespoon yogurt, 2 tablespoons chutney, 2 teaspoons curry powder, salt, and cayenne pepper in the bowl.

Add ground turkey, chopped green onion, and chopped mint to the mixture.

Mix thoroughly.

Shape the mixture into four 3/4-inch-thick patties.

In a separate bowl, combine chopped apple, remaining yogurt, remaining chutney, remaining curry powder, remaining onion tops, and remaining mint.

Prepare the grill to medium heat.

Spray the patties with nonstick spray.

Grill the patties for about 5 minutes per side, or until cooked through.

Cut one end off each pita bread.

Fill each pita with one burger, some lettuce, and one-quarter of the yogurt mixture.