You can make the pie in a standard pie plate or, for a prettier presentation, use a thin tart shell. The quantity of sugar depends on the sourness of your fruit; I like the pie a bit on the tart side. The most difficult part of this recipe is removing the seeds, especially if you use kumquats. Don’t forget to start the recipe the night before you plan to serve it.
1. Scrub the citrus under warm water with an abrasive scrubber. Rinse well. If using large citrus fruit like lemons or limes, cut off both ends of to expose the fruit (if using kumquats, this is not necessary). Then cut the citrus into paperthin slices (I like to use the slicing tube on my food processor.) Remove any seeds. Layer the citrus slices, zest and sugar in a large bowl. Toss gently and set aside for 30 to 60 minutes. Toss again. Cover and set aside at room temperature for 8 hours or overnight, stirring once or twice if convenient.
2. Preheat the oven to 350 degrees.
3. Stir the citrus mixture carefully and remove any remaining seeds. Whisk the eggs until light in a separate bowl, add them to the citrus mixture and mix well. Pour into the pre-baked pie crust or tart shell and arrange citrus slices as needed so that they lay flat in the crust or tart shell.
4. Bake the tart until the filling is set and lightly golden, approximately 25 to 30 minutes for a thin tart and 30 to 40 minutes for a pie. Rotate the pie in the oven midway through baking to ensure even coloring. Remove and place on a wire rack.
5. Serve the pie warm or cool. To keep the pie, wait until it cools, cover it and refrigerate. Bring it back to room temperature before serving.
Adapted from the China Moon Cookbook by Barbara Tropp.