Peel and quarter the potatoes and cut them into thin slices. Fry in hot oil for about 8 minutes. Rinse beans, drain. Peel and chop onion and garlic.
Remove the potatoes. Fry the minced meat in the frying fat until crumbly. Fry onion and garlic. Add tomatoes, beans and 150 ml water, bring to the boil, simmer for about 5 minutes.
Cut avocado in half, remove seeds, peel, dice finely, mix with lemon and season. Add potatoes to the minced meat, warm up. Season with salt, pepper and chili. Serve with avocado. Serve with sour cream and nachos.