Peel the sweet potatoes and dice, then cook in a pan of boiling water for about 10 minutes, until tender.
Meanwhile, slice the leeks and cut the sausage into small cubes. Cut the chilli in half, remove the seeds and chop.
Heat a little oil in a frying pan. Add the chorizo, leek and chilli. Gently fry for about 5 minutes, until the chorizo has released its fat and the leek has softened.
Drain the cooked sweet potatoes and the canned beans. Add these to the frying pan and cook for 5 minutes.
Using a fork or potato masher, mash the mixture roughly and press down into a flat cake. Cook for another 5 minutes until golden and slightly crispy on the bottom.
Meanwhile, if you like, make some poached or fried eggs in another pan.
Serve hot.