The night before you make your jam,
layer the berries and sugar together in a
very large bowl, then cover and set aside
at room temperature. This helps the
sugar to start dissolving so you don’t
run the risk of over-cooking the fruit
when you actually begin to make the
jam. The next morning, give everything
a quick stir, then set aside again until
you are ready to start cooking.
Before you start, put a small saucer in
the freezer. Tip the berries, scraping out
all juices and any undissolved sugar, into
a preserving pan, or a large, wide-based
pan (the wider and more open the pan,
the faster the jam will be ready so a
preserving pan is really ideal). Stir in the
lemon juice, then collect all the pips and secure them inside
a tea-leaf strainer or piece of muslin
before adding to the pan, too (cooking the pips along with the fruit extracts the pectin they contain, helping your jam to set).
Start the berries over a low heat until
all the sugar is completely dissolved, then
bring to the boil and simmer for 5 mins.
Turn off the heat and spoon a little hot
syrupy jam onto the chilled saucer. Once
cool, push the jam with your finger.
If it wrinkles a little, it’s ready and has
reached setting point. If it is too runny
to wrinkle, return the pan to the heat and
boil in 2-3 minute stages, removing the
pan from the heat each time you do the
saucer check, until the jam wrinkles.
Skim off any excess scum, then stir
in the knob of butter, if you want – this
will help to dissolve any remaining scum.
Leave the jam for 15 mins before ladling
into sterilised jars (see tip, below) – this
allows the fruit to settle so it doesn’t sink
to the bottom. The jam will keep in a
cool, dark place for at least 6 months.
Refrigerate jars once opened.