Cook the bacon, wash the lettuce, slice the red onion.
Make the Teriyaki Sauce
Mince the garlic, dates, and ginger. Add all ingredients to a small saucepan and bring to a simmer, stirring occasionally.
Allow to cook together for about 8-10 minutes, or until reduced enough that the mixture coats the back of a spoon.
Optional step: Strain the sauce through cheesecloth or a fine mesh sieve, pressing the mixture gently to separate all the liquid from the food.
Make the Patties
Mix the beef with the teriyaki sauce, salt, pepper, and garlic powder. Form into 4 patties.
Preheat your grill to medium heat. Set the burgers on the grill and cook for about 4-5 minutes per side for medium doneness.
Grill the Pineapple
Peel, core and slice the pineapples into 1/4 - 1/2 inch slices. Lay them directly on a well oiled and hot grill for about 3 minutes per side, but turn them often to prevent too much charring.
Assemble the Hawaiian Burgers
Fill each lettuce wrap with grilled pineapple and a burger patty, then pile it high with bacon, red onion, extra teriyaki. Enjoy!
Notes
Indoor cooking: Cook the burgers on the stovetop in a skillet over medium-high heat. Broil the pineapple slices on a lined baking sheet for about 3 minutes per side, just until they're charred, watching closely to avoid burning.To make in advance: Mix the burger ingredients together and form them into patties. Place them on a plate side by side and cover tightly. Set in the refrigerator for up to a day before cooking. Set the plate on the counter for about 30 minutes before cooking. This allows the burgers to come closer to room temperature before cooking.