Clean the leek, peel the carrots. Wash the vegetables and cut them diagonally into thin slices. Bring 1/2 litre salted water to the boil, add vegetables and cook covered for about 8 minutes. In the meantime wash fish fillet, dab dry and cut into 4 slices.
Sprinkle the fillets with lemon juice and salt lightly. Cut off the rind from the toast and crumble the slices. Mix softened butter, horseradish and a pinch of salt. Stir in first crumbs, then flaked almonds.
Pour the vegetables onto a sieve, drain well and place in a large ovenproof dish or 4 gratin dishes. Season with pepper, pour cream over the vegetables. Place fish slices on the vegetables.
Spread butter-horseradish crumbs on top. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 20-25 minutes. Baguette bread tastes good with it.