In a large skillet, heat the oil over medium-high heat. Cook the artichokes, olives, cauliflower, onions and lemon juice. Season the mixture with salt and pepper and cook for 10-12 minutes. While cooking place fish in a baking dish and top with the pistachios. Remove from the heat and pour over the fish. Bake the fish in the oven for 20 to 25 minutes, or until the fish is cooked through and flakes easily with a fork. Serve hot.