Add water, sea salt, dried onions and pepper to ground beef, and mix well
Form into patties, about 1/2 inch thick
Place hamburger patties separately on squares of aluminum foil, and form into loose foil packs
Add 1 cup water to Instant Pot, place trivet inside, and pile foil packs on top of trivet
Turn valve to sealing position, hit PRESSURE COOK for 15 minutes, and do a 5 minute natural release
Hit cancel, and when pin drops, open cover, and remove foil packs.
Open foil packs, place hamburger patties on baking sheet, brush each patty with a thin layer of barbecue sauce, and broil in oven for 5 minutes, or until top is brown and slightly crisp
Turn oven off, add cheese, if desired, and serve on buns with your favorite toppings