Rinse the quince thoroughly, cut into quarters, remove the core, cut into pieces. And immediately put it in the water so that it does not darken. Add the washed and chopped pitted lemon. Close the lid and cook after boiling for 20-30 minutes. Quince should be soft, it is easy to pierce it with a fork. This is very important, because we will wipe it through a sieve, and if the quince is not cooked, it will be very difficult to wipe.
By the way, in the original, they are boiled together with the seeds or boiled separately, and then marmalade is boiled in this broth, since the seeds contain a lot of gelling substances. This does not allow you to beat it with a blender and pass the sauce through a sieve for longer, so I went the easy way.