Zubereitung

1. 1

   Sterilise four screw-top jars of 250 ml each and their lids in a large pan of vigorously boiling water, then lift them out with tongs and let them drain on a clean cloth. Only germ-free jars keep the jam for a long time.

2. 2

   Pick the raspberries over, sorting out soft or mouldy fruit and small leaves. Fresh raspberries are not washed, or they fall apart and the jam turns watery.

3. 3

   If you like, push half the berries through a fine sieve to remove some of the little seeds, then add the pulp back to the whole berries.

4. 4

   Squeeze the lemon. Mix the raspberries, lemon juice and 2:1 jam sugar in a tall pan; frozen berries can go into the pan straight from the freezer, but then take a little longer to come to the boil.

5. 5

   Bring everything to the boil, stirring, then let it boil hard over full heat, stirring constantly, and skim off the pink foam. The jam sugar only sets to work at a rolling boil.

6. 6

   For the set test, put a blob on a cold plate; if it firms up after a minute, the jam is ready. If it stays runny, boil for another minute and repeat the test.

7. 7

   Pour the boiling hot jam straight into the prepared jars to about 1 cm below the rim, wipe the rims with a clean cloth and screw the lids on tightly at once.

8. 8

   The jars do not need to be turned upside down; simply leave them standing and let them cool completely. As they cool, the lids pull inwards with an audible click.