Wash and hull the strawberries, and place them in a saucepan with a splash of water and lemon juice (if using). Mash with a potato masher and simmer over medium heat for about 10 minutes until they've released their juices.

Strain the strawberry pulp through a jelly bag or dampened cheesecloth for at least 2 hours, preferably longer for a better yield.

It takes roughly 4 pounds of strawberries to make the 4 cups of juice needed for this recipe. If you're a bit short for any reason, add water or fruit juice.

Bring the juice to a boil on the stovetop and add the powdered pectin. (Don't add the sugar yet.) Return the mixture to a boil, stirring frequently to distribute the pectin, and boil hard for about a minute.

Add the sugar, and return to a boil. (This is important, don't add the sugar until last or the strawberry jelly may not set.)

Boil hard for about 1 minute, and then pour into prepared canning jars leaving 1/4 inch headspace.

Store in the refrigerator, or process in a water bath canner for 10 minutes. Turn off the heat and allow the jars to stand in the canner for an additional 5 minutes before removing them to cool.

Check seals and store any unsealed jars in the refrigerator for immediate use.