Onions are finely chopped, lowered for several seconds into boiling water and cooled quickly. Prepared onions are laid flat on the herring fillets, rolled up with rolls, packed tightly in a non-oxidizing dish, then filled with mustard dressing and allowed to stand in a cool place (4-8 ° C) for 8-10 hours. 
When feeding, the herring is watered by the same dressing and sprinkle with chopped green onions and finely chopped greens. 

Herring (fillet) 150-200 g, onions 1-2 heads, onion green 50 g, mustard filling 3/4 st.