Potted herrings in guinness

1. Wash herring fillets and roll up, starting from the tail.
2. Place in a baking dish and add the stout-and-vinegar mixture.
3. Add all other ingredients.
4. Cover with baking parchment or foil and bake in a moderate oven (about 350°F) for 20 minutes.
5. Remove from oven, allow to cool, and serve.