Wash the potatoes well and cut into pieces. Heat 4 tablespoons of oil in a large frying pan, fry the potatoes for about 15 minutes, turning them several times. Clean, wash and cut the peppers into pieces.
Clean and wash the zucchini and eggplant. Slice the zucchini and cut the eggplant into pieces. Wash the fish, dab dry and cut the skin several times on both sides at even intervals.
Wash the lemons, grate dry and cut into slices. Wash herbs, dab dry. Peel garlic and cut into slices. Season dorades inside and out with salt and pepper. Fill with herb twigs, lemon slices and garlic.
Brush with 2 tablespoons of oil. Place on a baking tray and cook in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 15-20 minutes. Add the vegetables to the potatoes, season with salt and pepper and fry everything else for another 10-15 minutes while turning.
Mix 100 g butter with lemon peel and season with salt. Pluck the lavender flowers. Mix 100 g butter with lavender flowers, also season with salt. Arrange the vegetables with the giltheads and the butter.
Garnish butter with lavender and lemon wedges.