Cut each potato in half, and place in a large ovenproof skillet; add water to depth of 1 inch. Bring to a boil; cover, reduce heat, and simmer 8 to 10 minutes or until potato is tender. Drain and set aside.
Combine flour, salt, and pepper; sprinkle evenly on both sides of fish. Coat skillet with cooking spray; add oil. Place over high heat until hot. Add fish; cook 2 minutes on each side. Remove skillet from heat; add potato, tomatoes, and wine. Sprinkle with dillweed. Bake, uncovered, at 425° for 8 minutes or until fish flakes easily when tested with a fork. Remove from oven, and drizzle with margarine. To serve, cut fish into 4 pieces. Serve with lemon wedges.