1) In a small bowl, toss the cheese with the cornstarch. Rub the garlic over the inside of a medium saucepan, then add the clove to the pan with the lager and bring to a boil. Add the cheese mixture in large handfuls, stirring until melted, and bring to a boil. Add the mustard, season with salt and pepper and simmer over moderate heat until thickened.
2) In a medium bowl lightly knead the Bison loosely and form patties ¾ inch thick. Season burgers with salt & pepper to tastes.
3) Grill over moderate heat 4 minutes each side
4) Serve with lettuce, tomato and top each burger with a generous portion of the cheese sauce