Zest of 1 large orangepared into wide strips with no white pith
1onionsmall, red or white, very thinly sliced
Instructions
Check the herring fillets for any pin bones and remove as necessary. Dissolve the salt in 500ml cold water to make a brine, then add the fillets. Leave for two to three hours.
Meanwhile, make the marinade. Put all the ingredients in a saucepan, bring slowly to a boil and simmer for a minute. Set aside to cool.
Drain the herring fillets from the brine and pat them dry with kitchen paper. Roll them up, skin side out, from tail end to head end, and pack the rolls into three sterilised 500ml preserving jars. Pour the marinade over the herrings, making sure you get some of the spices and zest in each jar, then seal.
Store in the fridge for at least three days before eating. They're best eaten five to 10 days from jarring, but will keep for up to a month. The longer you leave them, the softer and more pickled they'll get.