There are so many regional variations on the crusty Mexican "submarines" called tortas, each of which will represent the perfect torta for someone reading these pages. So I'll give you the basic architecture: They're built on the bottom half of a split crusty oval bun (some of the soft center bread pulled out, spread with mashed beans, topped with meat if you like (here, for expedience, I've mixed the chorizo in with the beans), and finished with cheese, avocado, something spicy and the crispy tops. There are two buns commonly used in Mexico for tortas: the oval, split-top, crusty "French" roll called a bolillo, and the softer, flatter, three-hump roll called a telera. Teleras are best for tortas that are crisped between the hot plates of a sandwich (panini) grill.
Set a very large 12-inch skillet over medium heat and add the chorizo. Cook the chorizo, breaking up the clumps, until browned and thoroughly cooked, about 8 to 9 minutes. Add 1 or 2 tablespoons of the oil, depending on how much fat the chorizo has rendered, and the beans. As the beans come to a simmer, mash them to a smooth paste with a bean masher, old-fashioned potato masher or the back of a large cooking spoon. Cook the bean mixture, stirring nearly constantly, until the consistency of very soft mashed potatoes, about 10 to 15 minutes total cooking time. Taste the mixture and season with salt, if necessary. Keep warm over the lowest heat, preferably covered to keep the beans soft and moist.
Heat a large griddle or skillet over medium heat. Slice the rolls open lengthwise. Use fingers or a spoon to scrape out some of the soft bread in the center of each piece, making a small hollow. Brush the insides with the oil, then lay them cut-side down on the griddle or skillet to crisp to a rich golden brown, about 2 minutes. Cook's Note: You may have to do this in batches if your rolls are large or if your griddle or skillet is small.
Smear about 1/2 cup of the chorizo-bean mixture over the bottom half of each roll. Cook's Note: You'll have about 1 cup of the mixture leftover; cover and refrigerate for a midnight snack.
Top the bean mixture with slices of the cheese and the avocado. Add a dash of hot sauce or spoon on the salsa. Set the top of each roll in place and you're ready to serve.
NotesCook's Note: Freewheeling Riffs on Tortas: Feel free to evolve this recipe as you like. Layer in sliced rotisserie, smoked, or grilled chicken. Use leftover roast pork or beef. Choose your favorite cheese. I love goat cheese on a torta. Grill some onions or add a final, full-flavored layer of pungent herbs like cilantro, Pueblan papalo or pickled chiles, jalapenos or smoky chipotles. For most Mexican cooks to consider it a torta, you'll need to keep that smear of beans. For me, you'll need to keep the avocado and salsa, too.