Sous vide cooking can be done at very low temperatures; 120 F for a rare steak, for instance. The only reason it’s not done in an oven is because the temperature control isn’t precise enough.
Slow-cooked lamb is the only way to cook lamb roast. Overnight at 70°C.
Also, cassoulet.
I cook nuts & bolts (chex mix) at ~250F
Brian
I often try that, since the rest of my house is too cool for bread rising in the winter. But it’s not easy to keep the temp low and even.
It would be so simple for oven manufacturers to extend the thermostat (or include a second one) down to 80-90F for such tasks, but I’ve never seen one like that.
What I usually do in that case is to set the oven for its lowest temperature (170F on mine), let it preheat, then put the bread in and turn it off. Yeah, it’ll cool down, but it’ll still be warmer than the kitchen countertop, and the only consequence of the temperature dropping below optimal is that it takes a little longer (but not as long as it would without the oven).
Once again I’m glad I live in a place where a warmer drawer is a standard part of the oven.
Cup of boiling water next to your dough bowl, in the microwave. (Or a pan of boiling hot water in the oven alongside the rising dough.)
I’m a fan of long rises though, so a house in the 60s makes for a nice slow rise and lots of flavor development, especially in sourdough.
You can actually do a quasi sous-vide approach by slightly freezing your steaks, searing them in a ripping hot pan, and then cooking them the rest of the way to 133-ish in a very low temp oven.
It also works pretty well in reverse (I think slightly better, actually)- cooking in the low temp oven to say… 130, and then searing quickly.
The reason I think it works better is because the outer surface dries out in the oven, and lets you get a much better sear witihout having to overheat the rest of the steak too much.
Have you tried letting it rise with the oven light on, assuming your oven has an oven light? My oven usually stabilizes around 85F if you leave the light on. Looking online, it seems some people’s ovens get as high as 110 if you leave the light on for several hours, but I’ve never tried it for that long, and of course it’s going to vary by the wattage of the bulb and the oven itself.
For overnight roasting of holiday turkey, set the oven a little bit above target meat temperature, say about 180, and leave it in there all night. Scaredy-cats and cookbooks covering their asses say it’s dangerous, but it makes a wonderful turkey.
The oven temp switch has only on and off. The thermostat turns the element on full until the setting temp is reached, then turns off until it cools below that temp, then back on again, constantly correcting for error. That’s how thermostats work. It costs no more to design the thermostat with a wide range of temps, than a narrow range, so why not use them?
I make yogurt in the oven with just the warmth of the oven light.
This is my favorite way to roast a turkey. I’ll start with an hour at 350° - recommended to kill any bacteria on the surface of the bird, then drop the temp to 190° and let it go all night. Nothing quite like waking to the aroma of a roasted turkey filling the house!!
Ever forget and leave a bag of pretzels or chips open so they got stale? How about a box of Cap’n Crunch or other cereal that has lost its crunch? Spread 'em out on a cooky sheet and pop them in a 225 degree oven for about ten minutes- good as new!
That sounds like food poisoning waiting to happen, mostly because the turkey will stay in the “danger zone” of 39-140 degrees F for the majority of the night, and essentially sit there and spoil at an accelerated rate versus even staying out on the counter.
Better to get a probe thermometer and cook at a normal temp right up to slightly below the recommended 165 degree temp, and let it coast up to 165 before serving.
Modern-day poultry doesn’t really benefit from low and slow cooking; it doesn’t have the intramuscular connective tissue that *some *cuts of beef and pork have, and that requires long slow cooking to convert said connective tissue’s collagen into gelatin.
Cooking a turkey to 165 internal is going to give you just as tender and juicy meat if you do it at 180 overnight as it will if you cook it in a 500 degree oven, as long as you don’t over cook it in either situation.
With poultry, I personally find fast, high-heat methods to work better in ensuring a moist bird than slow cooking methods. (A turkey may require spatchcocking/butterflying so everything cooks evenly, but a 3-4 lb. chicken does fine in one piece.) I assume that’s because with slower cooking there is just more time for the water to evaporate, perhaps? Plus you get nice, super crispy skin, which contributes to at least half my enjoyment of eating the bird.
When I was a kid, I took tae kwon do classes for two years; part of the martial art was board-breaking. My school had arranged with a local lumberyard to sell students boards of the correct size, so my father bought a stack of boards for me to use in class.
Someone had told my dad about making sure that the boards were well-dried-out, to make them a bit easier to break. He’d put them in the oven, set a very low temperature, to do this. However, one afternoon, while he was doing this, my mom then went to pre-heat the oven to make dinner. A few minutes later, we could smell wood smoke, and my dad raced over to pull the boards out.
They hadn’t quite burned, but they had some lovely scorch marks on one side, in the pattern of the oven’s rack. When I went to use those boards, my instructor was highly amused…he said to my father, “don’t use those when he goes to take his belt test, that’ll be too obvious.” 
I bake a few things at temps below 300, mostly custards and cheesecakes.
This is exactly what I do too. I also use the 170 degree setting to pre-heat my cast iron skillet.
You can re-flow solder on a PCB in your oven at around 200 degrees. Don’t tell the wife.
The best chicken skin spends a few days drying in the fridge first.
The Chefsteps Ultimate Roast Chicken recipe is supposed to deliver super crisp skin with sous-vide level moistness. My oven isn’t accurate enough to pull this recipe off but it does look intriguing.