I need to roast the Brussels sprouts at 350 for 40" and bake the sweet potatoes at 425 for 60" in one oven. How should I do it?
I have this problem frequently of needing to cook different things at the different temperatures in the oven at the same time. I tend to get around it by choosing the average temperature of the two (in your case ~390F) and adjust my cooking times appropriately. At 390F, I would cook for roughly the following times for your foods:
Brussels Sprouts 35" Sweet Potatoes 70"
They should could in a pretty similar manner to your recipe, but I'd keep an eye on them to ensure they come out perfect.
Hope that helps!
I've done almost exactly this many times. Your oven may differ from mine (hot spots, small, large, etc.)
I cut sprouts in half north to south, trim the tough part of stems, toss the sprouts lightly in some oil, spread them on a baking sheet of some kind, sometimes toss the sliced bacon pieces on top. Oven at 400. Some will brown a bit, which is my goal. Test them around 30 minutes. After they're done, I finish with kosher salt, pepper and sometimes lemon juice.
Baking sweet potatoes bare; not foil wrapped? Medium sized unwrapped potatoes may be done around 45 minutes (test with toothpick).
If you're committed to the 425 degree temp, delay putting the sprouts in (let the potatoes get a head start), then test the sprouts every 15 minutes, and toss them on the sheet, then another 15,etc. After they start to brown, you could lay some foil on top of them to allow time to cook the interior more.
If you're looking for a non-roasted sprout type of result, cover them with foil the entire cooking time and still check them every 15 minutes, otherwise, use steam.
I also vote for trading the foods between the racks and rotating the two sheets, but that's because my oven is small enough that this matters.