Combine the seasoning mix ingredients in a small bowl, mixing well. Set aside.
Combine the oil and onions in a 5 1/2 quart saucepan or large Dutch oven; sauté over
high heat until onions start to brown, about 6 minutes, stirring frequently. Stir in the
bell peppers and one tablespoon plus 1 teaspoon of the seasoning mix (reserve the
remaining mix) and cook about 3 minutes, stirring and scraping pan bottom frequently. Add
the tomatoes and garlic, stirring and scraping pan bottom well; cook about 3 minutes,
stirring occasionally. Stir in the stock and green onions. Bring to boil, stirring and
scraping the pan bottom occasionally. Continue boiling about 10 minutes, stirring
occasionally.
Remove from the heat and transfer mixture to a bowl. Let cool slightly, then cover and
refrigerate until well chilled, preferably overnight. NOTE: It is important to have the
sauce very cold or it will become too watery in the final cooking. Put it on ice to speed
the process if you're in a hurry.
Place chilled sauce in a 17 X 11-inch ungreased pan (2 1/2 inches deep). Gently stir in
the crab meat, being careful not to break up lumps and distributing crabmeat and sauce
evenly in pan. Arrange fish on top in single layer. Brush top of fish with melted butter,
then sprinkle with the remaining 2 teaspoons seasoning mix. Bake at 475 degrees just until
fish is cooked (flaky) and sauce is heated through, about 20 minutes. Do not overcook.
Remove from oven and serve immediately as is or with rice.