You don’t need to stick to 1kg fruit – just weigh your fruit and use the same weight of jam sugar, and allow the juice of 1 lemon to 500g fruit. Jam sugar has added pectin – vital for Strawberry Jam to set, but you can add pectin separately.
1 kg strawberries, stems removed
juice of 2 lemons
1 kg jam sugar
3 tsp of vanilla paste – to taste
Method
Put the strawberries and lemon juice in a large pan and heat gently for 5 minutes or so until the strawberries soften. Add the sugar and dissolve. Then turn up the heat and bring to a simmer.
Continue to simmer until setting point is reached. Test either with a thermometer to 105”C – or place a teaspoon of the jam on a cold plate and see if the surface wrinkles when pushed with a finger.
Just before setting point stir in the vanilla paste for the last few minutes of cooking
Pot into sterilised jars and cover. Store in the fridge after opening.