Rinse and drain the beans. Peel, pit and dice the avocado and mix the flesh with the lemon juice. Heat the oil in a pan, sauté the onion, add the mince and fry until crumbly. Stir in the tomato purée and season. Pour in the soup and bring to the boil. Add the pasta and cook until al dente, about 8 minutes. Stir occasionally. Add the beans and simmer for a few minutes. Flavour again with the spices. Serve garnished with the avocado cubes.