Defrost the fruits at room temperature.
Add them to a large pot on medium heat together with the lemon juice.
Boil for 5 minutes then turn off the heat.
Use a large sieve to separate the pulp from the seeds, skins and the small stems they have. I used a spatula to push the pulp against the sieve's walls and extract as much pulp as possible.
Add the obtained liquid to boil together with the brown sugar on low heat for one hour, while stirring from time to time with a spatula.
Dissolve half of aspirin on 1tbsp of cold water, add it to the jam and boil for a couple of minutes more. The aspirin here acts as a preservative.
You will obtain a runny liquid composition, only a little thicker than the original one, but this is ok as this way it can be consumed as it is on butter toast or you can use it to prepare steak sauces.
Add the jam to a clean jar and seal it tight. You don't have to keep it in the fridge as you added the aspirin as preservative. If you don't want to add the aspirin, then keep the jar in the fridge.
