Rinse lemon. With a vegetable peeler, pare yellow skin from lemon and finely chop. With a knife, cut off and discard white pith. Coarsely chop lemon, discarding seeds. In a 1- to 2-quart pan over high heat, bring to a boil 1 cup water, lemon peel, chopped lemon (with juice), dried apricots, sugar, minced fresh ginger, coriander seed, mustard seed, and hot chili flakes. Reduce heat, cover, and simmer for 5 minutes. Uncover and boil over medium heat, stirring often, until most of the liquid is absorbed, 10 to 12 minutes.
