Prepare about 1.5kgs of fruit (you can do more but it makes the straining more difficult). Cut up the quinces (I quarter them) and include cores and skin. Just cover with water and add a couple of tablespoons of lemon juice (helps with setting). Cook in a covered pan until completely pulped (I complete the pulping with a potato masher). Strain through a jelly bag (my bag is made from two old tea towels stitched together). Measure juice and allow ¾ cup of sugar to 1 cup of juice. Heat juice to boiling point. Remove from heat and stir in juice until dissolved. Return to heat and boil briskly until setting point is reached (I use the ‘drip’ test – when the drips from the stirring spoon begin to merge). Skim to remove scum (I don’t bother). Pour at once into sterilised jars. And gloat – or despair.
Store somewhere earthquake-proof.
I eat mine on toast.