Place a plate in the freezer. Combine 2 pounds rhubarb, 2 cups honey, ¾ cup cold water and juice of 1 lemon in a saucepan or Dutch oven set over high heat and bring to a boil. Reduce heat to medium-low and cook, stirring occasionally, until thick, about 45 minutes. Jam will continue to thicken as it cools.
Notes
CN's Jam Tips
Sweeten to taste. Rhubarb is quite tart, so I don't like to skimp on the honey. However, you don't want to make it overly sweet. I recommend tasting as you go and carefully adjusting/adding more sugar until it reaches your desired sweetness. Start with 1 ¼ cups and go from there.
Use very ripe strawberries. This will help the jam to turn out nice and sweet without a ton of added sugar. If the strawberries are not super ripe, you may need to add more sugar.
Use the plate test. Place a plate in the freezer to chill while the jam cooks. When the jam looks like it's done (coats the back of a wooden spoon), drizzle a spoonful of jam on the cold plate. If the jam "wrinkles" and doesn't run, it's set and ready to take off the heat. If it's still pretty loose, keep cooking the jam and try again in a few minutes.
Add salt. I learned this trick from a comment on a NYT recipe for apple jelly and have started incorporating it when I make jam. A big pinch of fine sea salt stirred into the jam pot will accent its sweetness.
Do half honey and half sugar. You can also make this jam using a combination of sugar and honey. Use 1 cup of honey and 1 cup of granulated sugar to sweeten the jam.