season ground beef with garlic, black pepper, and salt

wash the lettuce and reserve

cut the onion in rings, cook them on the grill and reserve

cook the ground beef in hamburgers shape (round)

clean the.portoblello mushrooms leaving only the top of it

cook the portobello mushrooms on the grill

assemble the hamburger: use Portobello mushrooms as bread

take one mushroom and put it up side down on the plate, on top of it put some lettuce, the grilled beef and onions, and some parmesan cheese, and finally another mushroom