After your fruit has been prepped as indicated above, combine the rhubarb, sugar, water, lemon juice, spent halves (with 1/8″ of the blossom and stem ends removed), and seeds in a large non-reactive bowl; set aside at room temperature for 1-2 hours.
Pour the contents of the bowl into a large, non-reactive pot; as you are spooning the fruit in the pot, set aside the lemon seeds and tie them up in a small cheesecloth bag. Add this bag to the pot and bring the ingredients to a boil over medium-high heat. Continue to cook, stirring the jam constantly, for about 15 minutes. Skim foam from the surface of the jam as necessary.
Drop the heat to medium and hold the jam at a constant simmer, checking often to ensure the jam isn’t scorching on the bottom of the pot. After 15 minutes, check to see if the jam is set by placing a small spoonful on a plate that has been in the freezer for at least an hour; the jam is set when it holds its shape on the cool plate. If it seems too loose, continue cooking it over medium-low heat until it’s set.
Remove the seed bag and spent lemon halves. Ladle the jam into hot, sterilized jars, leaving a 1/4″ headspace. Process in a hot water bath canner for 5 minutes if using half-pint or pint jars. Store in a cool, dark, and dry place for up to one year.
Sorry, there is no nutrition information available for this recipe.