1 Pour boiling water over the tomatoes but do not peel them, just dice them. Mix with the oil, vinegar, salt and ground black pepper and season to taste.
2 Season the fish with salt and ground black pepper and grease the bottom of a pot with butter. Place the onion in the pot and arrange the fish on top. Add the wine, place the lid on the pot and steam on a medium heat for 10-12 min.
3 Use a round biscuit cutter (6 cm diameter) to cut out portions of the fish. Place the cutter on a plate and place some of the tomatoes in side it. Spread evenly and then place the fish carefully on top. Garnish with the remaining tomatoes and the chervil.