Heat a 12-inch cast-iron skillet or other heavy pan over medium heat for 2 – 3 minutes. Add the oil and swirl to coat the bottom and an inch up the sides of the skillet. Add the chopped bell pepper and onion and cook, stirring occasionally, for 3 to 4 minutes or until starting to soften. 

Scoop the refried beans into the pepper/onion mixture and stir and mash to combine the ingredients well. 

Continue frying, stirring and scraping the pan every 5 minutes or so, until the bean mixture has darkened and reached the texture you prefer. You may need to add a few dribbles of additional oil if the mixture begins sticking to the pan.

Authentic refried beans are quite stiff in texture and develop a lacy crust on the bottom after about 30 minutes. Cooking for a little shorter time yields a creamier texture.

Push and flatten the bean mixture into a half-moon against the side of the pan and turn the burner off. Top with shredded cheese and allow the residual heat from the skillet and refried beans to melt it.

Serve as a side dish for entrees like enchiladas or arroz con pollo, or as a filling for burritos, for example.