Spanish Mackerel with Green Peas

Fry two tablespoonfuls of chopped onions in two ounces of butter, lay in the mackerel cut up into four ounce slices and when well fried, moisten with water, add a garnished bunch of parsley and salt and let the fish cook; when ready to serve add cooked peas (No. 2742); finish by thickening with a little veloute sauce (No. 415), egg-yolks and butter. Dress the fish, pour the peas over and serve.