- 1 1/2 pounds ground sirloin
- 1 shallot, finely chopped
- 2-3 tablespoons finely chopped fresh parsley
- 1 tablespoon Worcestershire sauce (eyeball it)
- Salt and freshly ground pepper
- Extra virgin olive oil (EVOO), for drizzling
- 3 tablespoons butter
- 1/2 pound crimini or white mushrooms, sliced
- 1/4 cup dry sherry
- 2 tablespoons Dijon mustard
- 4 eggy rolls, split and toasted, or 8 thick slices challah bread, toasted
- 1 small bunch watercress, chopped
- 1/2 cup chopped cornichons or baby gherkin pickles
- 1/2 pound truffle mousse pâté
In a medium bowl, mix together the meat, shallot, parsley and Worcestershire sauce; season with salt and pepper. Score the meat into four equal portions and then form into four large patties.
Heat a drizzle of EVOO in a large nonstick skillet over medium-high heat. When the pan is screaming hot, add the patties and cook for 4 minutes on each side for medium-rare, 6 minutes on each side for medium-well doneness.
Meanwhile, place a medium size skillet over medium heat. Melt 2 tablespoons butter in a drizzle of EVOO, add the mushrooms and cook until tender, about 6 minutes. Pour in the sherry and let it cook off, about 30 seconds. Season the mushrooms with salt and pepper and remove from the heat.
Stir together the mustard and remaining 1 tablespoon butter. Spread the Dijon butter liberally on the bun bottoms. Top with the watercress, a burger patty, a pile of mushrooms and a few chopped cornichons. Spread the mousse pâté on the bun tops and set them into place.