Mushroom ketchup is one of Britain's oldest condiments and still manufactured today. Here is a recipe to make your own concentrated umami rich mushroom essence. Use it to make a sauce with butter for a steak, or to pup up dark winter stews. —Fraser Wright
Break the mushrooms up into small pieces and toss them with the salt in a large porcelain bowl. Cover and leave to steep for 24 hours.
Transfer the mixture to a pan with the peppercorns and mace. Heat up slowly and simmer for 20 minutes. You don’t want it to boil but to let the mushrooms cook and the spices infuse. Leave to cool completely. Strain this through a sieve and squeeze all the excess juice out of the mushrooms.
Decant into a sterilised bottle or jar. Store in the refrigerator.