For the salsa:
1 mango, diced
1-1½ cups diced fresh pineapple
½ of one red bell pepper, diced small
¼ cup red onion, finely diced
1 tbsp. minced fresh cilantro
Juice of one lime
Pinch of coarse salt
For the sauce: (I halved it and had plenty for 4 burgers)
1 cup fresh chopped pineapple
½ cup low sodium soy sauce
1 inch knob of ginger, peeled and minced fine
3 tbsp. brown sugar
2 cloves garlic, minced
½ tsp. vinegar (apple cider or rice vinegar)
½ tsp. sesame oil
1 tbsp. cornstarch
1 tbsp. cold water
For the burgers:
1 lb. ground sirloin
2 tbsp. finely chopped yellow onion
1 tsp. minced garlic
1 tsp. salt
½ tsp. freshly ground pepper
1 or 2 dashes of Worcestershire sauce
To make the salsa, combine all the ingredients in a medium bowl. Toss to mix well. Cover and refrigerate, allowing flavors to blend while you prepare the sauce and burgers.
To make the sauce, combine the pineapple, soy sauce, ginger, brown sugar, garlic, vinegar and sesame oil in a blender or food processor. Puree until smooth and well blended. Transfer the mixture to a medium saucepan. Warm over medium-high heat until bubbly, about 1-2 minutes. In a small prep bowl, whisk together the cornstarch and water until smooth. Add the cornstarch mixture to the saucepan and stir until well incorporated. Continue heating the sauce, stirring constantly, until the mixture bubbles and thickens. Remove from the heat and set aside.
To make the burgers, prepare a charcoal or gas grill for direct grilling over medium-high heat. In a large bowl, mix together the beef, yellow onion, garlic, salt, pepper and Worcestershire sauce. Form the mixture into 4 patties, each about ¾-inch thick.
When the grill is heated, cook the hamburgers directly over medium-high heat, turning once, 3 -5 minutes per side. Check for doneness by cutting into a hamburger near the center or testing with an instant-read thermometer. No pink should show on the inside, and the internal temperature should register at least 160°F on an instant-read thermometer. A few minutes before the burgers are done cooking, grill the buns just until lightly brown and toasted.
To serve, place a hamburger patty on each of the buns. Top with teriyaki sauce and garnish with mango-pineapple salsa. Replace the top bun to form a sandwich and serve immediately.