0.6kg blackberries
300ml water
2.5kg jam sugar
Peel, core and slice the apples. To prevent them browning, put them into a bowl of water with a couple teaspoons of lemon juice.
After 10 minutes, test for setting point by dripping a small amount onto a cold plate. If, after a minute the jam doesn't run when the plate is tilted, poke it with your finger. If it wrinkles, the jam is done. If not, test again in a couple minutes.
Once the jam has reached setting point, turn off the heat. If you have a lot of white foam on the top, stir the pan a little as it cools, to stir the foam back into the mixture.
Makes about 10 jars.