Mix flour with pepper and dredge fish fillets in it. Heat large skillet and add oil. Cook fillets in oil about 3 minutes per side or until golden brown. Remove from pan and set aside. Drain off all but 2 tablespoons of oil. Add garlic and fry for 15 seconds. Add curry paste and saute for 1 minute. Add tamarind, fish sauce, soy sauce, and sugar. Cook for 1 minute. Stir in green onion and ginger. reduce heat and simmer for 2 minutes. Pour hot sauce over the fish and garnish with cilantro and tomatoes.