2 quince, peeled, cored, and coarsely chopped (6 cups)
3 strips lemon peel
2 cups sugar
2 Tbs. lemon juice
Simmer quince, lemon peel, and 6 cups water in covered saucepan over medium-low heat 40 minutes, or until soft. Drain, then purée in food processor. Return to saucepan, and stir in sugar and lemon juice. Cook over low heat 11/2 hours, or until pink and very thick.
Line loaf pan with parchment paper. Spread paste in prepared pan, and cool. Unmold onto cutting board, and slice.
Membrillo is traditionally served with cheese, bread, and also in a salad. 