Portobello Mushroom Burger

4       large Portobello Mushrooms (hamburger bun size)
1       pound ground grass fed beef or lamb
4       tablespoons of unsalted organic butter, raw butter, or olive oil
1       medium onion cut into 4 pieces
3-4    tablespoons crumbled feta cheese 
2       medium tomatoes sliced
3-4   ounces of raw, organic cheddar, or your favorite cheese sliced
Sea salt and pepper to taste

• Preheat the oven to 350 degrees.

• Carefully clean the mushrooms with a damp cloth or brush. You can also briefly rinse and dry the mushrooms with a towel. Cut off the stems with a knife. 

• Place the mushrooms on a baking dish with their cap facing down and their gills showing. 

• Melt the butter in a small sauce pan (skip this part if using olive oil). Add seasoning to the butter (olive oil) if desired.

• Drizzle the butter mixture (olive oil) on top of the mushrooms equally. 

• Toss the feta cheese on top of the mushroom gills.

• Mince the onion in a food processor. Mix in the meat and the seasoning using a fork.

• Divide the meat into 4 sections and shape each section into a patty that matches the size of your mushroom. Put each patty on its mushroom and place the dish into the oven for about 45 minutes.

• Put the cheese slices on top of the burgers and let them melt just before you remove the mushrooms from the oven.

• Add the tomato slices on top of the burgers. 

Tip: Asparagus roasted with butter and garlic on low heat are a great addition to these burgers.