The amount of cooked rhubarb and crushed strawberries should always total 3½ cups.
8-10 half-pint glass jars, One package of liquid Certo fruit pectin About 5-7 large stalks of rhubarb (1 cup when cooked) Ripe strawberries (2½ cups when crushed, about 1½ quart boxes) 6 cups of sugar
Wash the rhubarb and chop it into 1 inch chunks. Do not peel it. Using a large pot, put in just enough water to cover the bottom and add the rhubarb. On low heat, simmer and stir the rhubarb until it gets mushy and stringy. Do not boil it. Turn off the heat and remove from burner. Wash the strawberries and remove stems and caps. Crush the berries.
To make the jam: Add the crushed strawberries to the cooked rhubarb. Add the sugar and stir well. If desired, add the lemon juice to help firm up the jam (if you cut back on sugar you may want to add the lemon juice to keep the jam from being runny).
Place the pot on high heat and, stirring constantly, bring quickly to a full boil with bubbles over the entire surface.
Boil hard for 1 minute, stirring constantly.
Remove from the heat and stir in the liquid pectin. Skim any foam off the surface. Fill the jars and seal tightly. Let them stand for a few hours, then you can refrigerate if you like.
Consider putting a label on the jars to identify the recipe and date you made the jam. Always keep refrigerated after opening.