Damson Plum Jam (Mürdüm Eriği Reçeli)

Wash 1 kg (about 2.2 lb) of damson plums and cut each plum in half. Remove the pits, then cut each half into 4–5 more pieces. Pour 1 kg (about 2.2 lb) of granulated sugar over the top. Leave to rest for one full day. The next day, transfer to the stovetop and bring to a boil, then reduce the heat. Once the mixture begins to thicken and reach a jam-like consistency, squeeze in the juice of 1 lemon. Boil for another 5 minutes, then remove from heat.