Heat 2 teaspoons oil in a large saute pan over medium-high heat.  Add mushrooms and onion and saute, stirring occasionally, for 4-5 minutes or until the onion is soft and translucent.  Stir in garlic, and saute for 1-2 more minutes, stirring occasionally, until the garlic is fragrant.  Remove mixture from heat, drain off any extra juices or oil, and set aside.

Meanwhile, as the mushroom mixture is cooking, add the black beans to a large mixing bowl and roughly mash them with a potato masher (or the back of a spoon).  Add in the cooked mushroom mixture, breadcrumbs, egg white, steak seasoning, and stir well until the mixture is evenly mixed.  (If the mixture seems too wet, add in a few extra spoonfuls of breadcrumbs to help bind it together.)

Divide the mixture into four equal portions (each will be about 1/2 cup), and use your hands to form each portion into a large patty.  Set aside.

Rinse out the saute pan, then return it to the stove and heat the remaining 1 tablespoon oil over medium-high heat.  Carefully transfer the black bean burgers to the pan and cook on each side for 5-6 minutes, flipping once. If your pan is not big enough to fit all four burgers, you may need to do this in batches.

Remove from heat and serve the burgers on buns immediately, topped with Arla Muenster sliced cheese, fresh arugula, and/or any other toppings that sound good to you.