1 lb ground yak
6 baby portobello mushrooms
2 T. butter
5 T. balsamic vinegar
salt and pepper to taste
2 to 4 oz. blue cheese or chevre goat cheese
6 slices French bread, about ½ inch thick

Divide the yak into 6 patties, shaped to fit the French bread slices.  Salt and pepper to taste.  Grill or broil until barely pink inside.  Meanwhile, cut the stems off the mushrooms.  Melt the butter in a skillet over medium heat, then add the balsamic vinegar.  Place the mushrooms in the skillet and cook undisturbed until the edges start to brown.  Flip the mushrooms and cook the other side until brown.  Toast the French bread lightly, then spread a thin layer of cheese on each piece.  Top with a yak burger and then a mushroom.  Drizzle with a few drops of balsamic vinegar, and salt and pepper to taste, and serve immediately.