- Complexity: advanced
- 1 kg (2 lb) large open mushrooms, chopped
- 50 g (2 oz) salt
- 15 g (1/2 oz) ground allspice
- 1 small piece of root ginger, roughly chopped
- 2 mace blades
- 1 shallot, finely chopped
- 600 ml (1 pint) red wine vinegar
1. Layer the mushrooms and salt in a lidded jar. Cover, leave 2 days, stirring four times. Place in a saucepan with the remaining ingredients. Cover, simmer 30 minutes. Strain through fine sieve, pressing gently to extract all the juice, pour into hot sterilized screw-top bottles or bottling jars which must then be sterilized as follows to prevent fermenting: screw tops on loosely. Place bottles in deep pan, completely immerse in cold water while standing on a base of wire, wood or cloth - they will crack if they touch the bottom of the pan. Separate from each other with a cloth. Cover, heat the water, keep it at 77°C (170°F) for 30 minutes, or at 88°C (190°F) for 20 minutes. Remove bottles, place on a wooden surface to prevent them cracking. Tighten screw bands at once.
2. Leave 24 hours, test for a seal: remove screw-band, grip lid only with your fingers. If lid stays firm, a vacuum has been created; replace screwband. If lid comes away, use at once. As long as seal stays intact ketchup is safe to eat.
Makes: about 1.2 litres (2 pints)