Rinse the apples and lemon thoroughly under running water to remove any dirt or residue.

Quarter the apples and lemon, keeping the skins, cores, and seeds intact since they contain natural pectin.

Place the fruit pieces in a large saucepan with 300 ml of water. Cover and cook on very low heat.

Mix gently from time to time to prevent sticking. The apples will soften and turn into a chunky compote.

After about 1 hour of slow cooking, pour the mixture into a clean tea towel placed over a strainer. Let the juice drain into a large bowl.

After 30 minutes, press the fruit pulp to extract as much juice as possible.

Weigh the collected juice and add an equal weight of sugar.

Return the juice and sugar to the saucepan. Simmer on low heat, skimming off foam if necessary.

When the mixture thickens and turns amber, test by placing a drop on a chilled plate. If it gels and holds its shape, it’s ready.

Pour the hot jelly into sterilized jars, seal tightly, and turn them upside down to cool completely.