Preheat oven to 350° F. 

Spread butter on cut halves of boillos.  Place buttered side on a skillet over medium heat.  Toast for 2 minutes on each side or until bread begins to brown.   Remove from skillet and set aside. Let cool for 2 minutes.

Spread refried beans over toasted buttered sides of bolillos.  Arrange on a large baking sheet. Top with shredded cheese and topping of your choice.

Heat in oven for 12 minutes or until cheese melts and bubbles.  Remove from oven and enjoy.

Instructions for pico de gallo topping

Place all ingredients in a medium bowl.  Stir to combine.

Instructions for soy chorizo and mushroom topping

Heat oil in a large pan over medium heat.  Add soy chorizo and stir, breaking up into small pieces.  Add mushrooms and cook for 7 minutes or until mushrooms are tender. Remove from heat and set aside.

Instructions for rajas and corn topping 

Roast poblano peppers over a gas flame, turning frequently with tongs, until charred on all sides, about 5 minutes each.  Place in a plastic bag, set aside to allow steaming for 10 minutes.  Rub and remove the pepper charred skin with hands or paper towel. Cut peppers open, remove seeds and veins.  Slice into strips.

Heat oil in large pan over medium heat.  Add onion and cook for 2 minutes.  Add chile strips and corn kernels.  Season with salt.  Cook for 10 minutes or until corn is tender.  Remove from heat and set aside.