Squeeze 3 balls of meat from each sausage, then fry in the oil for 5 mins until golden. While they cook, put the potatoes on to boil for 10 mins until tender. Add the peppers to the pan, then fry for 4 mins more. Tip in the garlic and spices, fry for 1 min, then add the beans, tomatoes and sugar. Simmer for 5 mins until saucy and the meatballs are cooked.
Drain the potatoes, then crush with a masher. Fold through the yogurt and chives, loosen with a splash of water, then serve with the chilli. Top with a dollop more yogurt and sprinkling of chives, if you like.