Method
- Finely chop the mushrooms. Dice the onion. Melt the clarified butter in a frying pan and fry the mushrooms and the onions until all the moisture has evaporated. Season with salt and pepper to taste.
- Soak the bread slices for about 3 minutes in water then sqeeze them out. Put the minced beef, egg, mushroom mixture, herbs and bread into a bowl and mix thoroughly. Season with salt and pepper to taste.
- Divide the mixture into 4 and shape into 4 burgers. Grill on the barbeque for 8-10 minutes on each side. Cut the bins in half and toast the cut sides on the barbeque for 2-3 minutes.
- Meanwhile, mix together the mayonnaise and mustard and season to taste with salt and pepper. Thinly slice the cucumber.
- Spread the mustard-mayonnaise on the buns and place 2 lettuce leaves and several slices of cucumber on the base of each. Top each with a burger and cover with the other half of the bun.
