Preheat the oven to 350F. Dissolve the cornstarch in cold water and combine it with all the other ingredients, except chicken thighs, in a small saucepan. Cook over low heat until the sauce is thick and bubbly.
Place the chicken thighs in a 9 x 13-inch baking dish and brush them with sauce on both sides
Bake for one hour, basting with the sauce every 10 minutes, and flipping them once at the 30 min mark.