This is my other rhubarb jam recipe. Also very good...I actually don't like strawberry jam and I think this is pretty good as the rhubarb cuts the sweetness. My issue with this is that it doesn't use enough rhubarb, mostly strawberries.
4 cups strawberries (chopped...they said crushed....I chopped then mashed for a bit with my potato masher) - this was about 2 (16 oz) containers from my local store
2 cups chopped fresh rhubarb
1/4 cup lemon juice
1 pkg (1.75 oz) powdered fruit pectin - that's the small yellow box
5 1/2 cups sugar
Combine strawberries, rhubarb and lemon juice; stir in pectin. Bring to a boil rolling boil, stirring constantly. Stir in sugar, return to a full rolling boil. Boil and stir 1 minute.
Remove from heat and skim off foam. Ladle hot mixture into sterilized jars, leaving 1/4 inch headspace. Clean top. Put on lids and rims.
Place into canner and process at a boil for 5 minutes.
Makes about 6 pints (okay, so I did a double batch and I got 7 pints and 2 jelly jars so less than this).