Light a grill. Coat each fish lightly with flour, tapping off the excess. Oil the rack and grill the fish over a moderately hot fire until cooked through, about 5 minutes per side. Alternatively, heat 1/2 inch of vegetable oil in each of 2 large skillets and fry the fish over high heat until golden and crisp, about 5 minutes per side; drain on paper towels. Sprinkle the fish with salt and carefully transfer them to a large platter or dinner plates. Drizzle the sauce over the fish and serve right away, with rice.