Preheat the oven to 200°C/Fan 180°C/Gas 6. Toss the cherry tomatoes and chilli flakes in 1 tbsp of olive oil and roast in a large roasting pan for 10 minutes.
Season the skate wings with salt and pepper and transfer to the roasting pan, moving the tomatoes to one side. Roast for 15 minutes.
Make the dressing by gently melting the butter in a small non stick pan, let it cool for a while and then whisk in 2 tbsp's olive oil, the juice of a lemon and the mustard.
Pour the dressing over the fish and tomatoes and return to the oven for 10 minutes more.
The skate is cooked when the flesh can be lifted away easily from the centre bone.
To serve
Serve with a quartered lemon, the tomatoes and the pan juices.New potatoes go well to soak up the sauce.