Herring with fried onions

Salads and snacks 
from fish
Herring with fried onions
Onion is sliced ​​and fried until soft in vegetable oil, then tomato puree is added and frying is continued until the oil is colored orange, after which sugar, salt, ground pepper is added and cooled. 
When serving fried with tomato onions put on fillets of herring. 

Herring (fillet) 150-200 g, onions 1-2 heads, vegetable oil 10 g, tomato puree 15 g, sugar 10 g.