Peel the sweet potatoes and cut them into approx. 2 cm large, approx. 0.5 cm thick pieces. Cook in boiling salted water for about 5 minutes. Drain, rinse and drain well.
Pour the beans into a sieve, rinse and drain. Peel and roughly dice the onions. Peel garlic and chop finely. Heat 2 tablespoons of oil in a large frying pan. Sauté the sweet potatoes for about 3 minutes while turning them. Take out. Put 1 tbsp. oil in the pan and fry the minced meat for about 1 minute, turning it over. Add onion and garlic and fry for about 2 minutes, turning occasionally. Season with salt and pepper. Add tomatoes and beans, add broth, bring to the boil and simmer at medium heat for about 5 minutes.
Cut the avocado in half, remove the core. Peel avocado, cut flesh into fine cubes, mix with lemon juice, season with salt and pepper. Add sweet potatoes to the minced meat and cook over low heat for another 3 minutes. Season to taste with salt, pepper and chilli.
Arrange sweet potato pan, spread sour cream and avocado on top. Sprinkle with some chilli. Spread chips on the plates around the sweet potato pan.