Making marmalade always feels like a good use of citrus—you get the most from each part of the fruit—the floral essential oils in the peel, the pectin in the pith and seeds, and the sweet-tart juice and flesh. Ugli fruit has a thick layer of pith beneath the peel; to keep the marmalade from becoming too bitter, trim as much away from the peel and flesh as possible and tie it up in a cheesecloth bundle to simmer with the fruit and lend its pectin to the finished product. The general method for this recipe was adapted from
Food in Jars.