Soused herrings

1 pt white wine vinegar
½ tsp dried red chilli flakes
1 tsp brown mustard seeds
2 tsp mixed peppercorns
20 tsp sugar, in a little boiling water
1 onion, thinly sliced
Dill, finely chopped
8 herring fillets

Bring vinegar, chilli, peppercorns and mustard seeds to the boil, then cool.
When cooled, decant into a sealable jar or Tupperware, and add dill, onion and herrings.

Leave for 3 days before eating, ideally with rye bread.