(Makes 1 pint)
4 pink or red grapefruits, about 4 lbs.
2 cups sugar
1 cup chopped shallots
1 Tbs. fresh thyme leaves
Peel the grapefruits with a paring knife, carefully cutting away the skin without the white pithy part. If any has adhered, remove it. Slice the peel into thin strips and boil it in three cups of water for 10 minutes. (This will soften the peel and remove some of the bitterness.) Drain the peel.
Segment the grapefruits by cutting out the fruit wedges between the membranes. Remove any seeds. You’ll need three cups of segments. Squeeze the remaining membranes to get as much juice as possible. Combine the drained peel, the segments and juice, sugar, and shallots in a heavy-bottomed non-reactive saucepan.
Cook the marmalade over medium-low heat until it reaches 235°F, about 20 minutes. Stir every few minutes to make sure the bottom doesn’t scorch as it thickens. Pour into a heat-proof container and let it cool to room temperature. Stir in the thyme leaves. Cover and refrigerate for up to a month.