Plaice is available fresh or frozen and can be bought whole or as fillets. Plaice cooks very quickly - fillets should only need a total cooking time of 4-5 minutes, whether grilled, fried or poached.
Bake in the oven for 15- 20 minutes until caramelised. While the cauliflower is roasting in the oven cook the plaice. Pat the fillets dry with some kitchen paper to remove excess water.