Wash berries and place them in a medium saucepan over low heat. Once the berries are warm, muddle them in the saucepan until no large pieces remain. (Optional: Use a food mill at this point to deseed the mixture.)

Add the sugar and lemon juice; stir until well combined.

Using a separate bowl, mix the cornstarch and water until well combined. Add this mixture to the saucepan; stir until well combined.

Increase heat to medium-low, and bring to a boil. Stir frequently to ensure jam doesn’t burn.

Once the jam reaches 220°F degrees (~15-20 minutes), remove it from the heat and allow it to cool at room temperature. (If needed, you can skim and discard any foam that may be on top.)

Once cool, store in an airtight container in the refrigerator.