Cut up the onion and carrot into small rings, and put them into a stewpan with the herbs, mushrooms, bay-leaf, cloves, and mace; add the butter, and simmer the whole very gently over a slow fire until the onion is quite tender. Pour in the stock and sherry, and stew slowly for 1 hour, when strain it off into a clean saucepan. Now make a thickening of butter and flour, put it to the sauce, stir it over the fire until perfectly smooth and mellow, add the lemon-juice, give one boil, when it will be ready for table.
Time: Altogether 2 hours.
Sufficient, half this quantity for two slices of salmon.