The perfect jam for the holidays and wintertime!
First, dice up the strawberries into manageable pieces. Put the cranberries, strawberries, and raspberries into a large non-stick pot.
Next, heat the fruit up in a large, non-stick pot over medium-high heat, stirring and mashing often. You want to break down the fruit with a metal or wooden spoon. Make sure to stir frequently to decrease the risk of burning!
Once the fruit is heated up and starts to boil, mix one cup of sugar and the box of pectin in a separate bowl. Gently pour into the fruit and whisk well, eliminating any lumps.
Stir the remaining 2 1/2 cups of sugar into the mixture, one cup at a time. Whisk well each time.
After all of the sugar is mixed in, add the lemon juice.
Bring the jam up to a rolling boil and let boil for one minute as you stir continually. DO NOT stop stirring. You can burn the jam at this point.
Remove from heat. Ladle into the jars, leaving 1/4 inch headspace. Process half pints and pints for 10 minutes, 15 minutes for quarts.