Wash, dice and measure rhubarb, add to a large pot.
Wash lemon. Zest, add to pot, then juice and add that juice to pot as well.
Wash, peel, core, dice and measure the apples. Add to pot.
Add water and sugar OR liquid stevia to pot, stir, put on stove top and bring to a boil, then lower to a simmer uncovered for 15 minutes, stirring frequently after it gets going to avoid scorching at the bottom.
Add the cranberry, cinnamon, nutmeg, and added juice (optional)
Simmer a bit more until just thick enough to stand up on a spoon (about 5 to 10 minutes)
Pack into quarter-litre (½ US pint / 8 oz) jars.
Leave 2 cm (½ inch) headspace.
Wipe jar rims.
Put lids on.
Process in a water bath or steam canner.
Process for 10 minutes; increase time as needed for your altitude.