INGREDIENTS
2 lb
ground beef (85-percent lean)
Kosher salt and freshly ground black pepper
1/4 cup
Dijon mustardÂ
3 tbsp
soy sauce
1 tsp
sugar
6
slices Swiss cheese
1 tbsp
olive oil
8 oz
chopped baby bella or cremini mushrooms
2 tsp
fresh thyme leaves or 1 teaspoon dried
2 cloves
garlic, minced
6
yeasty buns