In a 12 to 14-inch saute pan, heat the olive oil over medium heat until just smoking.
Season the fish on both sides with salt and pepper. Add fish to pan and cook for 3 minutes. Turn fish when cooked and add cucumber, pepper, and lemon leaf (or lemon zest). Cook for another 2 minutes.
Add white wine and cook until evaporated, about 2 minutes. Add the passata and tomatoes and continue cooking for another 2 minutes. Season, to taste, with salt and pepper, sprinkle with parsley, and serve immediately.