Fish and vegetable gratin

Method

1. Preheat the oven to 180°C.

2. Peel the beetroot, use rubber gloves for this operation if you are vain! Chop the beetroot flesh into cubes.

3. Melt the butter in a sauté pan, add the beetroot, toss, add the cream, allow to bubble for a few minutes. Season with salt and freshly ground pepper and sugar. Taste and add a little more lemon juice if necessary. Serve immediately. Season the fish with salt and freshly ground pepper.

4. Arrange the fillets in a single layer in an ovenproof dish (it should be posh enough to bring to the table).

5. Mix the grated cheese with the mustard and cream and spread carefully over the fish. It can be prepared ahead and refrigerated at this point. Cook in a preheated oven for about 20 minutes or until the fish is cooked and the top is golden and bubbly. Flash under the grill if necessary.

6. To cook the beetroot, leave 5cm of leaf stalks on top and the whole root on the beet. Hold it under a running tap and wash off the mud with the palms of your hands, so that you don’t damage the skin; otherwise the beetroot will bleed during cooking. Cover with cold water and add a little salt and sugar.

7. Cover the pot, bring to the boil and simmer on top, or in an oven, for one to two hours, depending on size. Beetroot is usually cooked if the skin rubs off easily and if it dents when pressed with a finger. If in doubt test with a skewer or the tip of a knife.