2      tablespoons   vegetable oil -- lard, bacon or
                        -- chorizo drippings
   1      medium        white onion chopped
   4                    garlic cloves -- peeled and finely
                        -- chopped
   4      cups          undrained -- seasoned cooked
                        -- beans, slightly
                        -- warm
                        salt -- to taste
     1/2  cup           crumbled mexican queso fresco -- queso anejo,
                        -- pressed, salted
                        -- farmers
                        cheese -- dry feta or
                        -- parmesan, for
                        -- garnish
                        tortilla chips -- for garnish
In a large well seasoned or nonstick skillet, heat the oil or pork fat
over medium heat. Add the onion and cook, stirring frequently, until
deep golden, about 10 minutes. Stir in the garlic, cook for a minute
or so, then use a slotted spoon to scoop in about 1/4 of the beans,
leaving most of the liquid behind. With a bean or potato masher, or
the back of a large spoon, mash the beans into a coarse puree. Add
another portion of the beans, mash them in, and continue until all the
beans have been added and coarsely mashed. Add about a cup of bean
liquid or water and stir frequently over the heat until the beans are
still a little soupier than you'd like to serve them (they'll thicken
as they sit.) Taste and season with salt if needed.