Put the cranberries, water, sugar, salt, lemon juice and red pepper flakes in a small saucepan and bring to a boil over medium heat. Reduce to a simmer and cook, stirring now and then, until every berry has burst and the pan has gone cloudy, about 10 minutes.

Strain through a fine sieve, pressing hard on the solids, and scrape the thick glaze clinging under the sieve back into the bowl. Return the liquid to the pan and simmer 3 to 5 minutes more, to a scant 1/2 cup that coats a spoon. Set aside; it should be warm, not cold, when it meets the meatballs.

Heat the oven to 425F and line two baking sheets with parchment. Stir the cornmeal into the milk in a medium bowl and leave it 5 minutes to soften, then beat in the egg, herbs, salt and pepper. Add the pork and fold it through gently; working it hard makes the meatballs tough.

Take roughly a tablespoon of the mixture, press a mozzarella pearl into the middle, close the meat over it and roll between your palms until the surface is completely smooth and about 1 1/4 inches across. Any visible seam will open in the oven.

Wrap each meatball around its equator with a half slice of prosciutto, overlapping the ends underneath, and set it seam side down on the sheets with space between them. Repeat with the rest.

Bake 12 to 15 minutes, rotating the sheets halfway through, until the prosciutto is tight and crisp at the edges and a meatball reads 160F at the center. Do not move the trays in the first 5 minutes or the wrapping springs open.

Tip the hot meatballs into a large bowl, spoon over enough warm glaze to coat them, and turn them gently. Serve on cocktail picks straight away, while the ham is still crisp.