For the tapenade: Pulse the olives, capers, anchovies and garlic in a small food processor until pureed. Gradually add the olive oil. Season with lemon juice and pepper.
For the fish: Preheat the oven to 400 degrees F\200 degrees C. Pat the fish dry with paper towels. Place on a baking sheet and smear each with a spoonful of the tapenade. Put a few slices of tomato on top, drizzle with some olive oil and sprinkle with salt, pepper and herbes de provence. Bake until the fish is cooked, 6 to 8 minutes.