250g of butter or margarine
4 medium onions, finely chopped
1 fish stock cube dissolved in 4 cups of water
40g of vinegar
Salt
Pepper
250g of butter or margarine
4 medium onions, finely chopped
1 fish stock cube dissolved in 4 cups of water
40g of vinegar
Salt
Pepper
In a small saucepan with a thick bottom, combine the chopped onions, fish stock, vinegar, salt, and pepper
Cook over low heat, stirring occasionally, until the liquid has reduced by three-quarters
Place the saucepan in a bain-marie and gradually add the butter or margarine, in small pieces, while continuously whisking with an electric mixer
Serve warm, drizzled over hot fish.
