heat grill with direct heat on one half of the grill. Form 4 patties, seasoning with salt and pepper on each side.
Place pineapple and mushroom on the grill, 1 minute on each side. Place in a skillet with teriyaki sauce, chopping up the pineapple and mushroom with a spatula. Place on the top rack of your grill.
Place patties on direct heat, flip after one minute and continue to sear for another minute. Move patties to indirect heat and place cheese on top. Optionally you can brush on teriyaki in stead of using cheese. Cook for about 5-7 minutes until reach desired doneness or 165F
with a little butter on the the bottom of each bun, place on the indirect heat, or a cast iron griddle on the side burner until buns are nice and toasted.
Place burger on bun with any condiments you like, followed by a healthy topping of the pineapple portabella mushroom teriyaki sauce. Enjoy!