Heat enough oil to coat the bottom of a sauté pan large enough to fry both fish. Season fish with salt and pan-fry on both sides until cooked through and the skin is crispy. Remove fish and set aside. After draining the oil from the pan, fill a quarter way with water and let simmer. Add potatoes and scotch bonnet pepper. In a mortar and pestle, lightly pound bell pepper, garlic and a few pinches of salt and pepper. Add this mixture to a bowl, along with onions and carrots, and mix together with mustard and vinegar. After potatoes and scotch bonnet pepper have been cooking for about five minutes, add the onion mixture and let simmer for another 15 minutes. Then add fish and bouillon cube to the pot and let simmer for another 10 minutes, until potatoes are cooked through and the sauce has reduced and thickened. Remove pot from heat and adjust seasoning. Using a straining ladle, distribute the sauce, potatoes, scotch bonnet pepper and fish over a platter of steamed white rice.