Place 4 tablespoons olive oil in blender with cilantro, garlic, ginger, cumin, coriander, anise, cayenne pepper, 1/4 teaspoon salt and lemon juice. Process until smooth.
Cut fish in 4 or 6 portions. Season with salt and pepper. Place in dish, and coat with mixture. Marinate 2 hours.
Meanwhile, heat oven to 300°F Place tomato halves in tagine or in baking dish. Brush with 1 tablespoon olive oil, season with salt, and bake 1 1/2 hours, then chop coarsely.
Heat remaining oil in skillet. Add onions and peppers, and sauté about 5 minutes. Add eggplant, and sauté 5 minutes longer. Add tomatoes and olives. Season to taste.
Place mixture in tagine or in baking dish, or leave in skillet if it is ovenproof and has a cover. Place fish on top of vegetables. Cover tagine, baking dish or skillet. Place in oven to bake for 20 to 30 minutes, or simmer on top of stove over low heat, about 15 minutes. Garnish with cilantro and serve.