- 4 cups fresh kumquats (1 1/2 lb with leaves; 1 lb without)
- 1 cup water
- 2 cups plus 2 tablespoons sugar
- 1 teaspoon fennel seeds, lightly toasted
- 2/3 cup ricotta
- 1/3 cup sour cream
- 1 (12- to 13-inch) baked sweet tart shell
- Special equipment: an electric coffee/spice grinder
- Thinly slice kumquats crosswise with a sharp knife, discarding seeds.
- Bring water and 2 cups sugar to a boil in a 2-quart heavy saucepan, stirring until sugar is dissolved, then simmer syrup, uncovered, 5 minutes. Stir in kumquats and simmer gently 10 minutes. Drain and cool kumquats in a sieve set over a bowl, then return drained syrup to pan and boil until reduced to about 11/3 cups, 3 to 5 minutes.
- Finely grind fennel seeds in coffee/spice grinder, then transfer to a bowl and whisk together with ricotta, remaining 2 tablespoons sugar, and a pinch of salt just until ricotta is slightly smoother. Whisk in sour cream until just combined and spread evenly over bottom of tart shell.
- Arrange kumquats as evenly as possible over ricotta using your fingers or a small spoon, separating slices as necessary with a skewer, then brush kumquats with some of reduced syrup.
- Remove side of tart pan.