In a food processor: Add vegetables and squeeze in juice from a lime wedge - blend until smooth
Make roux with the butter and flour (whisk until browned) and then slowly add the jalapeno/tomato mix.
Add Cajun seasoning to taste (appx 2 teaspoons)
Add 1/2 cup of the half-n-half used to marinate the fish and simmer until flavor is dispersed throughout.
Cook the fish however you like and introduce some of the sauce (appx half) just before the fish is completely cooked. Remove the fish, retain the sauce and mix it back into the left over sauce from earlier. Drizzle sauce over the fish and serve.