In a large saucepan or stockpot, heat 1/2 cup vegetable oil over medium-low heat. Add 6 tbsp all-purpose flour and cook, stirring, until the roux is a light blonde color. Don't let it get too dark. Add 2 medium onions (chopped) and 2 cloves garlic (minced) and cook until the onions are softened. Add 1 (28-ounce) can stewed tomatoes (undrained and mashed; or two 14.5-ounce cans), 1/2 (10-ounce) can tomatoes with green chile peppers (Ro-Tel is one brand, spicy or mild), 2 (15-ounce) cans cream-style corn, 2 (15-ounce) cans whole kernel corn, and 1 quart chicken broth (low sodium or unsalted); cook over low heat at a simmer for 45 minutes. Meanwhile, peel & devein 2 lbs shrimp. Rinse the shrimp with cold water. Add the shrimp to the soup mixture and continue to simmer for about 10 more minutes. Season the soup with kosher salt and freshly ground black pepper to taste. Serve the soup hot and enjoy!