Heat a large iron skillet or whatever large sauté pan you have, on medium-high heat. When the pan is hot, melt 2 tablespoon of the butter and add the onions and bell peppers. Stir to coat with the butter and reduce the heat to medium-low. Cook the onions and peppers, stirring often, for approximately 15 to 20 minutes, or until they’re nicely caramelized, salt and pepper to taste. Remove from the pan and set aside.
Heat the pan back up on medium-high heat and add 1 tablespoon vegan butter and let it melt. When the butter is melted, add the mushrooms and stir until coated in the butter. Cook, stirring often, approximately 10 minutes, or until the mushrooms have lost their water and are a nice golden brown, salt and pepper to taste. Remove from the pan and set aside.
Drain the liquid (reserve 1 cup) from the soy curls and press out the excess broth. Add to the hot pan and cook for approximately 5 to 7 minutes, or until the edges are crispy and brown. Add a bit of the broth to deglaze the pan and let it evaporate. Stir often. Salt and pepper to taste.
Grill or toast the bread if desired. We suggest spreading a thin layer of melted butter or olive oil on the inside of the bread before toasting.
Build your sandwich. We like to start with the soy curls, then the veggies, and top it with the cheese sauce.