2. Place quince pieces in a large sauce pan with lemon zest, vanilla, and cover with water. Bring to a boil and then reduce to a simmer. Cover with a lid and and cook for about 30 minutes until quince is tender.
3. Strain the water from the quince. Discard the vanilla pod. Puree the quince in a food processor or blender. Measure the quince puree and use the same amount of sugar as puree for the next step.
4. Return the quince puree to the pan and add the sugar. Bring the heat to medium-low and stir the puree with the sugar until the sugar has dissolved. Add the lemon juice.
5. Cook over low heat stirring occasionally for 1-1/2 hours until the quince paste is thick with a pink hue.
6. Line a 11 x 9 inch baking tray with parchment paper. Pour the quince into the tray and smooth the top with a spatula. Chill in the refrigerator over night.