Kiluvõi (herring butter)

Instructions

1. Drain the herring fillets and remove any bones if needed, then chop them finely with a knife.
2. Very finely slice the onion, or grate it for a more melting texture.
3. In a bowl, mash the softened butter with a fork until smooth.
4. Add the herring, onion, vinegar and pepper, then mix until you have a uniform paste.
5. Taste and adjust with a little sugar if the herring is too sharp.
6. Chill for 30 minutes to firm up, then serve on rye bread.