Drain the beans in a colander and rinse. Mash into a pulp in a bowl, for example with a fork. Add the finely chopped onion, cheese, breadcrumbs and egg. Finally, season with salt and pepper.
Heat the vegetable oil (1 tablespoon or as needed) in a pan. Dust your hands with flour and shape about 8 small or 4 large burgers out of the mixture. Fry in a hot pan on both sides until dark brown for 8-10 minutes.
Tastes great in a classic way in a burger bun with lettuce, tomato and pickles. Also very tasty cold as a snack, for example with a salad.