About 45 minutes before serving, in dutch oven heat salad oil; in it saute garlic and onion until golden (about 10 minutes). Add tomatoes, potatoes, chili pepper, seasoned salt, 1-1/2 tsp. salt, red pepper, Tabasco, 3 cups water, 1 cup milk; stir occasionally, while bringing to a boil, then simmer, covered, 20 minutes.
Meanwhile, in 1-1/2 cups water and 1/2 teasp. salt in skillet, simmer flounder fillets 6 minutes, or until fork-tender but still moist. Also, beat cream cheese with 1/4 cup milk until very smooth. Now stir cream-cheese mixture, then shrimp and corn, into soup; cook over medium heat 5 minutes. Next, drain flounder fillets, divide each in half crosswise, then place a half in each of 6 soup plates. Spoon hot soup over fillets, garnish with mint sprigs and serve at once.