1½ pounds ground chuck (80% lean), for patties
½ teaspoon garlic powder, for patties
½ teaspoon kosher salt, for patties
½ teaspoon freshly ground black pepper, for patties
1 large mango, cut into ½-inch dice , or approx. 1 cup, for salsa
2 tablespoons roughly chopped fresh cilantro leaves, for salsa
1 tablespoon fresh lime juice, for salsa
1 medium serrano chile pepper, seeded and minced, for salsa
¼ teaspoon kosher salt, for salsa
4 thin slices pepper jack cheese
4 hamburger buns, split
Dijon mustard, to taste
Combine the patty ingredients, keeping the mixture crumbly rather than compressed. With wet hands, gently form four loosely packed patties of equal size, each about ¾ inch thick. Don’t compact the meat too much or the patties will be tough.
Using your thumb or the back of a spoon, make a shallow indentation about 1 inch wide in the center of each patty. This will help the patties cook evenly and prevent them from puffing on the grill.
In a nonreactive bowl combine the salsa ingredients. Toss gently and then refrigerate for at least 30 minutes or up to 1 hour. (After an hour, the fruit starts to become mushy.)
Prepare the grill for direct cooking over medium-high heat (400° to 500°F).
Grill the patties over direct medium-high heat, with the lid closed, until cooked to medium doneness, 8 to 10 minutes, turning once when the patties release easily from the grate without sticking.
During the last minute of grilling time, place a slice of cheese on each patty to melt and toast the buns, cut side down, over direct heat.
Spread the bottom half of each bun with mustard, and serve the patties warm on the buns topped with salsa.