In a large frying pan or cast iron skillet, heat the oil. Add the onions and 1/2 tsp salt and cook until softened, stirring occasionally, about 5 minutes. Add garlic and cook another 1 to 2 minutes, until fragrant. Remove the pan from the heat.
In a large bowl, dry the beans with a paper towel and then mash with a potato masher until beans are smashed but with some large pieces. Add the cooked onion and garlic mixture, flour, egg, chipotle peppers, cumin, remaining salt and cinnamon and stir well to combine. Place in the refrigerator for at least 30 minutes or until ready to fry.
Using the same pan (give it a wipe with a paper towel), add 1/3 cup scoop of the burger mix to the pan. Don’t over crowd the pan so work in batches. Flatten scoop with a spatula. Cook for 4 minutes, or until golden and crispy. Carefully flip each burger and cook for an additional 3 to 4 minutes
Transfer burgers to a plate. Serve with your favourite buns and fixings. You can also use these patties for salads, patty melts, grain bowls and as a simple side dish.