Mix the flax seeds with 2 or 3 Tbsp water and set aside. You should get a thick paste within 5 minutes.
Meanwhile, put the beans in a mixing bowl, then roughly mash them with a fork.
Grate the onion and mince the garlic. Add these to the beans together with the spices, flax mixture, tomato purée and chipotle. Then chop the grilled red pepper and add to the mixture, together with the chopped coriander. Season with salt and pepper, then combine the mixture with your hands until you get a sticky dough. Rest in the fridge for 10-30 minutes.
If you’re using the oven, set the temperature to 180°C.
Divide the mixture into 4 big, 6 medium or 8 small, equal portions and form patties. Put these on lined baking sheet, spray them with oil, then bake for approx. 15-20 minutes until golden, then turn them over and bake again for 10 minutes.
To fry the patties: heat a griddle or frying pan. Spray or brush the patties with oil, then cook them for 3-5 minutes on both sides until golden.
Serve them warm or at room temperature.