Preparation

Make the candied kumquats

• 片the kumquats crosswise 1/4 inch thick. In a small heavy saucepan, bring 3 cups water to a boil. Add the kumquats; bring to a simmer, and cook for 1 minute. Drain the fruit in a strainer and reserve. Rinse the pot, and add 3/4 cup cold water and the sugar. Bring the mixture to a boil, stirring until the sugar dissolves. Cook until the syrup is clear, then boil briskly for 1 more minute. Return the kumquats to the pot, and simmer, stirring occasionally, until the fruit is tender, 10 to 12 minutes. Let cool. (You can prepare the kumquats up to a week ahead. When cool, transfer the fruit and syrup to a glass jar, cover with a lid, and refrigerate until ready to use.)

Make the salad

• In a large bowl, whisk the kumquat syrup, vinegar, harissa, and a pinch of salt. Whisk in the oil. Add the celery to the bowl, and toss to coat.
• Peel the clementines, removing all of the white pith. Break into segments, and add to the bowl. On a cutting board, using a thin, sharp knife, cut the peel and pith from the grapefruit; cut to separate the fruit from the membrane, and add the fruit to the bowl. Cut the peel from the oranges, then slice crosswise into 1/3-inch-thick rounds; add to the bowl. Add the chopped mint, and toss well, then transfer to a serving platter or individual plates.
• Crumble the goat cheese over the salad, and sprinkle with the pistachios. Dot generously with candied kumquats, and dust with cinnamon. Garnish with small mint leaves.