Begin by crushing the cut strawberries in a large bowl. 

Mix together the strawberries, sugar, and lemon juice and let sit for at least an hour. 

Transfer to a saucepan and begin to stir over low heat until the sugar is dissolved.

Increase heat until high, and bring the strawberry mixture to a full boil.

Continue to boil, stirring constantly, until the mixture reaches 220 degrees F (105 degrees C) or is the thickened consistency of jam.

Transfer to hot sterile jars, leaving 1/4 to 1/2 inch headspace, and refrigerate. The jam will hold in the refrigerator for a month or two. You can also use a canning method to preserve this jam too.