Preserve spring rhubarb in a sweet soft-set jam for spooning over desserts or yogurt. Just three ingredients and very simple instructions. Makes 3-4 120g jars (2-3 340g jars). I prefer using smaller jars so that the jam is used up more quickly
Make sure to sterilize your jars, lids, and rings before you begin. You can run them through the dishwasher or wash them with hot soapy water. If choosing the latter, make sure to rinse them well and dry them with a clean tea towel.
Make Rhubarb Jam
Rinse the rhubarb stems in cool water and then trim the leaves and bottom of the stem. Slice the stems into 1/2" pieces and place them in a large saucepan. Pour the sugar over the rhubarb, stir to cover all the pieces, and then let sit overnight. You can leave the fruit on the counter but make sure to cover it with the pan lid.
Overnight the sugar will have drawn the juices out of the rhubarb and the pieces will look slightly shriveled. Pulling the juice out of the 'fruit' will help keep the pieces from falling apart completely in the jam-making process.
Now place the pan on your hob and bring to a boil. Add the lemon juice and stir carefully for about five minutes, trying not to break up the pieces.
Bottling the Rhubarb Jam
Spoon or funnel the jam into clean, sterilized jars and screw the lids on fully but not super tight. This is called finger tight.
Though most people don't water-bath jams and jellies in the UK, it's a far safer food preserving practice. Water bath canning both sterilizes and preserves high-acid food like jams, jellies, pickles, and chutneys. Doing this extra step will ensure that your preserves won't go off, grow mold, or otherwise become inedible.
Water Bathing the Jars
Lower the jars into a large pot of boiling water using a jar lifter. It's best to have a rack or folded up tea towel at the bottom of the pan so that the jars don't come into direct contact with the main heat source. Make sure the water covers the jars by about an inch and that there's at least half an inch of space between the jars and the pan and between the jars themselves.
Wait for the water to come back to a boil. After it has, set a timer for 10 minutes. Next, take the jars back out and set them on a towel on the kitchen counter. Leave them for at least 12 hours to cool down. With metal lids, you'll hear pops as the lids seal. Tattler lids don't make this sound so don't worry if you don't hear anything. When cooled, store in a cool cupboard but refrigerate after opening. This jam has a shelf-life of 12 months.
Learn more about why people in the UK don't water bath preserves here.