Strawberry freezer jam is a simple four-ingredient recipe (no pectin required) that's perfect for strawberry season. This small batch recipe makes a sweet jam that's filled with fresh strawberry flavor. Recipe makes about two 8-ounce jars.
In a saucepan over medium heat, add chopped strawberries, granulated sugar, lemon juice, and cornstarch. Stir occasionally until sugar has dissolved (and add a splash of water if your strawberries are not very juicy). Bring to a simmer, then reduce heat to medium-low. Simmer for 10 minutes, stirring occasionally.
Remove from heat and gently mash strawberries with a potato masher until desired consistency is reached. Return to heat and cook for another 5-7 minutes, or until mixture has reduced slightly. The mixture should thickly coat the back of a spoon (and will continue to thicken as it cools).
Remove from heat and allow to cool before transferring to jars. When filling jars, leave about 1 inch of space at the top - your jam will expand slightly when frozen. Cool jam completely before adding lids. Store for up to 1 year in freezer, or up to 3 weeks in the refrigerator.
Freezer jam is not shelf stable and needs to be stored in the refrigerator or freezer at all times. Jam will keep in the refrigerator for 3-4 weeks in a tightly sealed jar, or in the freezer for up to a year.
Sugar can be substituted with a sweetener alternative, but please consult your sweetener package for proper ratios (some are more concentrated than others).
If using a sugar substitute, keep in mind that the sugar helps preserve the jam, so your sugar-free jam will not keep as long in the refrigerator.