Put the beans, spring onions, tomatoes, chilli and coriander in a bowl with lots of seasoning and 1 tsp of olive oil. Toss together.
Heat 2 tsp of olive oil in a non-stick frying pan. Stir-fry the prawns for a minute then add the spices and cook for another 2-3 minutes or until the prawns are cooked through. Pile the bean mix onto tortillas, and top with the prawns and soured cream to serve.