Place the cherries in a pot and add 1¾ cups of water, or just enough to cover them. Cook over medium-high heat until the water comes to a boil, then reduce the heat to medium and simmer for 7–10 minutes until the cherries are tender. Stir in the red wine, sugar, zest, salt, pepper, ginger (if using), and star anise (if using), and cook for an additional 5 minutes. In a small bowl, dissolve the cornstarch in 2 tablespoons of water, then add it to the cherries, stirring well. Continue to simmer, stirring constantly, until the sauce becomes thick, glossy, and clear, about 2–4 minutes. Transfer the sauce to a bowl and set aside.