Sweet Saucy Smokies
Add the cornstarch before heating the sauce. If you forget, just make a slurry with a bit of water. Do not cook the smokies for an extended period because they will render their fat and turn the sauce into a greasy mess that won't cling to the sausages.
If using a tart jelly (like cranberry), add a tablespoon or two of granulated sugar until the sweet and sour taste is balanced. Caution, the sauce is hot, so be careful when tasting!