Heat the bacon fat in a small saucepot over low heat. Cook the onions, jalapeños, garlic, salt and pepper for 3-4 minutes. Turn heat to medium and add tomato paste. Cook 4-5 minutes, stirring constantly. Add remaining ingredients, except oysters and simmer for 10-15 minutes, stirring occasionally.
Using a kitchen towel, hold each oyster firmly. Insert an oyster knife in the small opening between the shells where the oyster is hinged. Gently pry open the oyster. Loosen the oyster from the shell by carefully running the knife below the oyster, keeping the oyster liquor in the shell. Discard the top shell.
Top each oyster with a heaping teaspoon of the sauce.
Prepare the grill. Grill the oysters, shell side down over direct high heat for 4-5 minutes. Use tongs to remove the oysters from the grill and serve immediately.
Yield: 4-8 servings