Clean the fresh hawthorn berry and then soak in slightly salted water for around 20 minutes. Then wash again and remove the core.
Transfer hawthorn into a food processor, add water. Blend until almost smooth but there are some small particles or smooth according to your own taste.
Pour the mixture to a sauce pan; add sugar and simmer for around 80 to 100 minutes. Add fresh lemon juice in the middle. Stir from time to time.
Pour the jam into the prepared containers. Leave 1/3 of space at the top of each container to allow room for the jam to expand in the freezer.
Seal the containers and let the jam sit at room temperature for 24 hours. Then store the jam the refrigerator for up to 1 week or in the freezer for up to 1 month.
Notes
For a longer storage time, you can add increase the amount of sugar used in the recipe.