Once they’re blistered all over, put them in a large plastic bag, seal it and wait for them to cool. You’ll then easily remove the skin (which is rather hard to digest).
Cook the skate in a pan of salted, aromatic boiling water (herbs or spices). The cooking time varies with its thickness (15 minutes for me from boiling point). The flesh should come away from the cartilage.
Remove the skin with a knife and lift the flesh off the cartilage.
When the skate and peppers are cold, take a terrine and line the bottom with cling film. Start by laying down a layer of peppers, a layer of skate, salt and pepper, capers, then start again with a layer of peppers, skate… until you run out of ingredients. No need to add a binder — skate contains a kind of « natural gelatine ».
Leave to rest for at least a day.