Bring a large saucepan of lightly salted water to a boil. Add pasta and cook for 8 to 10 minutes or until al dente. Drain and set aside.
Heat butter in a large frypan. Add the prawns, salt, pepper and paprika. Stir with a wooden spoon. When the prawns become pink (it should take 2 to 3 minutes), remove them with a slotted spoon, leaving the cooking liquid in the frypan.
Add red and green capsicums, shallots and garlic. Cook stirring for about 3 to 4 minutes over medium high heat. Add brandy and return prawns to the frypan. Cook over medium heat for a further 2 minutes.
Add sour cream, yoghurt and stir to coat all ingredients. Add coriander and bring to a simmer for about 30 seconds. Do not boil or sauce will separate. Serve over cooked fettuccine.