Preparation Steam potatoes until almost tender, about 8 minutes. Cool. Melt butter with 2 tablespoons oil in heavy large pot over medium-high heat. Add onions; sauté until golden brown, about 8 minutes. Mix in 3 tablespoons oil and garlic. Add potatoes; cook 2 minutes. Mix in red wine. Boil until almost no liquid remains, about 4 minutes. Add stock, tomatoes with juices and oregano and bring to boil. Add olives; boil until liquid thickens slightly and potatoes are very tender, about 12 minutes. Mix in 3 tablespoons parsley. Season with salt and pepper. Meanwhile, sprinkle fish with salt and pepper. Heat 1 1/2 tablespoons oil in each of 2 heavy large nonstick skillets over medium-high heat. Add fish fillets and sauté until just opaque in center, about 3 minutes per side. Arrange potatoes in center of each of 6 plates. Spoon some sauce over. Top with fish. Spoon remaining sauce over fish. Sprinkle with 1 tablespoon parsley. Drizzle with 1 tablespoon olive oil and serve.
Preparation Steam potatoes until almost tender, about 8 minutes. Cool. Melt butter with 2 tablespoons oil in heavy large pot over medium-high heat. Add onions; sauté until golden brown, about 8 minutes. Mix in 3 tablespoons oil and garlic. Add potatoes; cook 2 minutes. Mix in red wine. Boil until almost no liquid remains, about 4 minutes. Add stock, tomatoes with juices and oregano and bring to boil. Add olives; boil until liquid thickens slightly and potatoes are very tender, about 12 minutes. Mix in 3 tablespoons parsley. Season with salt and pepper. Meanwhile, sprinkle fish with salt and pepper. Heat 1 1/2 tablespoons oil in each of 2 heavy large nonstick skillets over medium-high heat. Add fish fillets and sauté until just opaque in center, about 3 minutes per side. Arrange potatoes in center of each of 6 plates. Spoon some sauce over. Top with fish. Spoon remaining sauce over fish. Sprinkle with 1 tablespoon parsley. Drizzle with 1 tablespoon olive oil and serve.