Heat vegetable oil in a medium saucepan over medium heat. Add onion and bell peppers for 5 minutes, or until they start to soften and onions become opaque.
Add pulled pork, diced tomatoes, ancho chili powder, garlic powder and water. Combine and heat for an additional 5 minutes.
Divide mixture onto 6 rolls. Add cheese or crispy onion straws, if desired.
Most grocery stores will have a small section in the produce department with pre-chopped vegetables, especially onions and bell peppers. The type of onion and bell pepper is not that important because the BBQ sauce flavor outweighs the vegetable, so you can use whatever you have leftover in your refrigerator. The left over tomatoes can be tossed into a package of 90 second ready rice and served as a side.