1. Heat oil in a frying pan. Sauté the onions and garlic until softened. Add cayenne and black pepper, and cook for a minute. 2. Add the chutney and fish stock. Simmer over a gentle heat for 5 minutes to ensure the mixture doesn't dry out. 3. Add prawns and cook until pink and tender. Add a bit of water if the sauce thickens too much. Simmer for 2 minutes. 4. Stir in parsley and season with salt. Serve with crusty buns and fresh lemon wedges.