Start with the mackerel: Arrange the 12 fillets in a large dish, cover generously with coarse salt, and let drain for 1 hour. Rinse well under cold water, pat dry with a clean cloth, and transfer to an ovenproof dish.
Thinly slice the onion and celery. Heat the sunflower oil in a pan over medium heat and soften the vegetables.
Slice the carrots into thin rounds. Layer them over the fish with the coriander seeds, fine salt, peppercorns, thyme, and bay leaf.
Drizzle with raspberry vinegar and white wine. Bake in a preheated oven at 170°C (th. 5/6) for 4-5 minutes. Remove and cool in the cooking juices.
Plate the mackerel and spoon the juices over top for a fresh, aromatic finish.
