While I consume most of my grapes in liquid form, I do look forward to fall harvest in the Upper Midwest, when I can pick up little red grapes just bursting with acidity. They're great on their own, but when roasted they gain extra depth without simply turning into a sweet grape jam. That also means that they play well with others, acting like a tart sauce.
They also cook quickly, finishing in ten minutes. As it just so happens, walleye fillets cook in basically the same amount of time. (Walleye is a firm-fleshed fish from northern Lake Michigan, but you can substitute another white fish, like cod or haddock.) Because the grapes already have such strong flavor, the fillets are only topped with a couple slices each of garlic and lemon.
To round out the meal, I decided to add some small fingerling potatoes. Thanks to their size, they don't take much time at all compared to other potatoes, but they did need a good 20 minutes. While that prevents this from being assembled all in one go, you just need to start them off in the roasting pan for the first ten minutes, before you add in the rest of the ingredients.