Cauliflower Gratin with Pickled Celery
1 large whole cauliflower
olive oil, for drizzling
salt and black pepper, for seasoning
¼ cup parmesan cheese, grated
¼ cup roughly chopped walnuts
2 tbsp finely chopped parsley
1 tsp grated lemon rind
1 stalk celery, sliced (leaves reserved)
1 tbsp lemon juice
pinch of salt
Easy mustard bechamel
2 tbsp plain flour
500ml full-cream milk
¼ tsp salt
2 tsp Dijon mustard
For the pickled celery, combine the celery, lemon juice and salt in a press-seal bag and squeeze out as much air as possible. Chill in the fridge for at least 30 minutes.
For the bechamel, melt the butter in a small saucepan then add the flour and heat for 2 minutes, stirring, until foaming. Add the milk a little at a time, stirring constantly to remove lumps, until a thin sauce is produced. Simmer for 5 minutes, then stir in the salt and mustard. Set aside.
Preheat the oven to 200°C.
Remove leaves from the cauliflower and trim the stalk so the head sits flat. With a small, sharp knife cut a deep cross into the base of the stalk (this will help it cook more evenly). Place the cauliflower into a large saucepan and cover with cold water. Add 1 tbsp of salt and bring to a boil. Continue to boil for 15 minutes then remove and drain.
Place the cauliflower head on a small gratin or baking dish and drizzle with the olive oil. Season with salt and pepper and bake for 30-40 minutes, until the cauliflower is tender and lightly browned.
Pour the bechamel over the cauliflower and scatter with the parmesan cheese. Grill for about 5 minutes until the bechamel and cheese brown. Scatter with the walnuts, parsley, lemon and pickled celery, then grind over more black pepper and scatter with the reserved celery leaves. Serve immediately.