Rach's creamy mushroom topping and a beef burger patty topped with melted swiss cheese on a brioche bun makes for the ultimate burger.
- 2 tablespoons olive oil
- 3 tablespoons butter
- 1 ¼ pounds brushed and cleaned mushrooms: hen-of-the-woods or maitake mushrooms, pulled into florets, crimini mushrooms, thinly sliced and stemmed, shiitake mushrooms, thinly sliced
- 2 large shallots, finely chopped
- 6 cloves garlic, grated or finely chopped (OR 1 bulb black garlic, pasted)
- 2 tablespoons fresh thyme, finely chopped
- Salt and black pepper
- About 2 tablespoons smoked shoyu, tamari or soy sauce
- ½ cup dry sherry or Shaoxing Chinese rice wine
- ½ cup crème fraiche or heavy cream
- 1 ½ to 2 pounds (6- to 8-ounce patties) ground sirloin 80-85%, or plant-based meat substitute (two 12-ounce packages—Rach likes Impossible Burger)
- 2 tablespoons Worcestershire sauce
- About 3 tablespoons grated white or yellow onion
- Kosher salt and coarse black pepper
- 2 tablespoons prepared or freshly grated horseradish, optional
- Canola or avocado non-aerosol cooking spray
- 8 slices Emmentaler Swiss cheese (Rach likes Finlandia)
- 4 brioche rolls
- Sweet and spicy cornichons or other pickles, finely chopped
- 1 cup upland cress or watercress
Heat a large skillet with EVOO, 2 turns of the pan, over medium to medium-high heat and melt butter into oil, add mushrooms and cook, stirring occasionally, 15 minutes to deeply brown and a little crispy at edges. Add shallots, garlic, thyme, salt and pepper to mushrooms and stir 2 minutes, add soy and sherry or wine and let it absorb, stir in crème fraiche or heavy cream, cover and remove from heat.
Heat a cast-iron skillet or griddle pan over medium-high heat.
In a bowl, combine beef or plant-based meat with Worcestershire, grated onion (grate directly over the bowl so the juice falls into meat) and season liberally with salt and pepper. Add in some horseradish for extra-spicy patties. Mix ingredients quickly – don't overwork it, and then form an even mass, score into 4 equal portions, then form 4 patties a little thinner at center than edges for even cooking.
Spray pan lightly with oil and cook burgers 7-8 minutes, turning occasionally, then top each patty with 2 slices of Swiss cheese and cover, remove from heat and let stand 1 minute to melt cheese.
Assemble: bun bottom, sweet n spicy chopped pickles, lettuce, Swiss cheeseburger, creamy mushrooms and cap with top of bun.