about 2kg (4lb 8oz) crab apples, or small wild apples, stalks removed
2–3 handfuls of ripe blackberries
about 1kg (2lb 4oz) granulated sugar
First, sterilize your jam jars: wash them in hot soapy water, rinse them, then put them upside down in an oven at 100°C/200°F/ gas mark 1⁄2 until they are hot and dry. Or, put them through the dishwasher on its hottest setting.
Roughly chop the crab apples – skin, cores, pips and all; or pulse them in a food processor until they are broken up. Place in a large, heavy-based pan or preserving pan with the blackberries. Pour over enough water to just cover the fruit. Place the pan over a high heat and cook for 20–30 minutes, or until pulpy. If the pan looks dry at any point, add a splash more water to cover the fruit again.
Pour or ladle the fruit into a jelly bag set over a large, clean bowl. Or, you can use a large sieve lined with a clean muslin cloth. Allow the pulp to drain for 3–4 hours or even overnight. To get the clearest of jellies, avoid the temptation to squeeze or push the pulp too much – a light press with a spoon is all you need.
Measure the fruit liquid into a heavy-based pan. For every 500ml (17fl oz) liquid, add 375g (13oz) sugar. Place the pan over a low heat and stir the liquid until the sugar has dissolved, then bring it up to a rolling boil. Boil for 8–10 minutes, then start testing for setting point. To do this, turn off the heat, spoon a few drops of the jelly onto a chilled saucer (from the fridge) and return the saucer to the fridge for 2–3 minutes. Push the chilled drops of jelly with the tip of a spoon; if the surface wrinkles, you’ve reached setting point. If not, boil the mixture for another 3–4 minutes and test again.
(If you’re using a thermometer, boil until the mixture reaches 103°C/217°F.)
Allow the jelly to cool a little, then pour it into the sterilized jars and seal straight away. You can keep the jelly like this for up to 12 months.