Place a skillet over medium-high heat, add olive oil.

Add mushrooms and stir. Cook for about 6 minutes, then season with red pepper flake, ginger, garlic, thyme, salt, and pepper. 

Add 1/8 cup of water and cook for about 5 minutes add the lemon juice and stir. 

Readjust the season if necessary, allow the liquid to dry. Sorry I mistakenly deleted the final product picture.

Place a saucepan/skillet over medium-high heat. Melt the butter add the onion, season with salt, and pepper. 

Cook the onion for about 15 minutes.

Preheat the skillet or cast-iron griddle over medium-high heat.

In a shallow bowl, add the ground beef, add the balsamic vinegar, grated onion, rosemary, knorr, garlic, olive oil, salt, and pepper. Mix together, don't overwork the beef.

Form patties let the middle a little thinner, thinner than the edges to allow even cooking.

After forming the patties to the size you like, cook the patties on the griddle/skillet. Turn to the other side and cook, it took about 6-8 minutes depending on the patty size.

When it is almost done, place a single slice cheese over each patty, if you want it all melt over with a foil to allow the cheese to melt faster without overcooking the patty.

Remove and repeat the process if you still have more patties to cook. You can toast the bread or just assemble without toasting the buns.

To assemble the burger: Smear some sauce or mayo over the bottom bun, add lettuce (if you're using), sliced tomato.

Beef patty, mushrooms, and onions.

Lastly, place the top bun covered with sauce/mayo.