I am a screaming hot kind of guy! I don’t have a ton of time and I love the caramelization from a hot oven. I do agree that in some cases low and slow does contribute to a depth of flavor we cannot achieve with the dial buried on 500F
So here is another perspective from Bon Appetit
Stop Roasting Your Veg in a Screaming-Hot Oven
FEBRUARY 4, 2016 / WRITTEN BY AMIEL STANEK CONTRIBS
When we talk about the Vegetable Revolution—you know, that whole thing where restaurants are cooking veg we actually want to eat—we place much emphasis on treating our veggie friends like meat. Sear them in a pan. Roast them in a hot oven. Char them on the grill. The idea is simple: Caramelization makes just about anything taste better, and aggressive cooking over high heat is the best way to achieve it. This is also why so many of our roasted veg recipes often call for a 400°-plus oven.
But lost in the whole “cooking veg like meat” conversation is the fact that, well, hot-and-fast isn’t the only way we like to cook our meat. And if low-and-slow cooking makes a succulent, fork-tender mess out of a pan full of short ribs, does it do something equally delicious to, say, a bunch of carrots?
Yes. Yes it does.
We’re not talking about a wet, braise-y, cooked-to-death situation here—though we absolutely love veggies cooked in that way, too. We mean dry roasting that veg with a little olive oil, a good sprinkle of salt, and a sprinkle of chile flakes for good measure—in a 250° degree oven until the exterior gets all shrivel-y and the interior takes on a delicate, custard-like texture. This is less about adding brash browned notes than it is concentrating natural flavors, yielding vegetables that taste distinctly and deliciously of themselves.
This custardy cauliflower purée brought to you by a low, low oven.
Whole farmers’ market carrots cooked in this way take on a beautifully concentrated sweetness, and take anywhere between an hour and an hour and a half. A halved head of cauliflower might take up to two and a half hours to become tender, but the result—moist, rich, deeply satisfying—is worth the wait. Thick wedges of winter squash. Whole peeled beets. Peppery radishes. All rendered slowly, quietly irresistible, waiting for nothing more than a sprinkle of finishing salt and a drizzle of olive oil or melted butter.
The timing will change depending on what kind of veg you’re using (obvs), and how large your pieces are, but the technique is about as low stakes as it gets—just taste as you go and pull your pan when it tastes delicious. One thing we can promise you: When your oven’s at 250°, there’s no way in hell you’re going to burn anything.