1: Wash and brush 800 g quinces, but do not peel, as the skin add to the flavour.
2: Cut the quinces into quarters, then remove and discard the core. Cut each quarter into small pieces. Put the quince pieces into a saucepan, add ½ lemon cut into 4 and just enough water to cover. Note: From 800g of quinces, you should be left with 500 g of cut fruit.
3: Put the pan uncovered on medium heat and cook until the fruit is soft enough for the point of a knife to go through it easily.
4: After cooking, discard the lemon pieces and pass the quinces through a vegetable mill on "fine" setting. Do not throw away the cooking liquid.
5: Transfer the quince pulp into a saucepan and weigh it (from 500 g cut fruit, you should be left with about 350 g of cooked pulp). Weigh 30% of this weight in cooking liquid (100 g here), then mix this with the quince pulp. You can add the zest of 1 orange at this point.
6: Weigh 450 g granulated sugar (this should be the same wieght as the mixture of fruit pulp and cooking liquid). Take out 50 g of this sugar at mix it separately with the 30 g jam sugar.
7: Put the saucepan on high heat and bring to the boil, then tip in the 50 g of sugar with its gelling agent.
8: Mix well, bring back to the boil and cook for 3 minutes, stirring constantly.
9: Add the rest of the sugar all at once.
10: Mix well, bring back to the boil and cook for a further 3 minutes, stirring constantly.
11: Pour into a mould or tin, lined with a sheet of cooking parchment. Leave to cool for at least 1 hour.
12: Turn out and cut into pieces about the size of a sugar cube.
13: You can make the paste look more attractive by rolling the pieces in a little granulated sugar, but this is not essential.
Remarks
This is a very ancient sweetmeat, particularly appreciated at the French court during the Renaissance. It was apparently a favourite of both Marie de' Medici and the Duc de Guise.