The essentials of roasting
Like sauté, "roast" is defined by what instructors in culinary schools call dry heat—that is, cooking without the cooling, moderating effects of water. It can be divided into two sub-techniques: high-heat roasting and low-heat roasting.
Terminology about roasting is erratic given that there’s no difference between roasting and baking. A roast recipe may once have referred solely to meats cooked over an open flame, whereas baking referred to anything cooked in an enclosed oven. Today we typically say we roast meats and we bake doughs and batters. That will be the distinction here (even though we do bake ham, we don’t roast meat loaf, and we both bake and roast potatoes).
High heat is used to develop flavour. Browning the skin of fowl and the exterior of meats makes it taste delicious. We use low heat for cooking larger items uniformly. Thus, we roast a chicken in a very hot oven to develop flavour, and we roast a big prime rib in a low oven to cook the center before the exterior is overcooked.
Because roasting does not involve water, and water is required for dissolving the connective tissue that makes meats tough, we usually don’t roast tough cuts of meat. You would not roast a pot roast because it would go from tough to dry. I do roast a leg of lamb, on the other hand, for flavour; after being cooked, the tough collection of muscles is tenderized by being cut into thin slices.
What to consider before roasting
That’s really all there is to know about roasting. It’s one of the simplest, most common, and best methods of cooking. It also fills up the kitchen with irresistible aromas. When you are determining how to roast something, think about its qualities:
- Is it naturally tender?
- How big is it?
- Does it have skin (which is mostly water that needs to cook off before browning happens)?
- Is your goal to make the exterior tasty or to have the item cook uniformly all the way through?
Lead image courtesy of Williams-Sonoma.
The three steps before roasting
There are only a few matters of finesse in oven roasting. They apply to other forms of cooking and are mainly common sense.
1 Let your food come to room temperature before roasting it.
2 The food also should be relatively dry; any moisture has to cook off before the good roasted flavours can develop.
3 Always preheat the oven.
I almost always do high-heat roasting at 425°F/220°C/gas 7 to 450°F/230°C/gas 8. At the higher end, all fats begin to smoke, so you need a clean oven and a ventilation fan for the most efficient roasting temperatures. For large cuts such as a big roast, I use a low oven, 225°F/110°C/gas ¼ or so, which is virtually a poaching temperature, especially given that moisture evaporating off the surface of the food has a cooling effect on the food.
Many ovens come with a convection feature, meaning a fan in the oven can be activated to continuously circulate the air. Convection is especially helpful in achieving a crispy skin on poultry because the moisture cooking out of the skin is carried away from the bird. Convection also prevents hot and cool spots in your oven. I recommend convection cooking for most high-heat roasting. Because the circulation makes the heat more efficient, acting as a kind of turbocharger, convection cooking can be faster than cooking without convection. Pay attention to how your convection works and adjust your cooking times accordingly.
How to achieve caramelization
To put it generally, use high heat to develop flavours of what we call caramelization (though you’re not actually caramelizing anything unless you’re baking a tarte Tatin). Caramelization, the sweet, savory complexity of roasted things, only starts to happen at temperatures of 300°F/150°C and higher. If you only want to cook something through without developing additional flavours, and without overcooking the outside while keeping the inside rare, use temperatures well under 300°F/150°C. The roasting vessel
Don’t cover food that you’re roasting. Covering food will result in steamed food rather than roasted food. Putting a top on a pan or covering it with aluminum foil is a method more like a braise than a roast because it turns what would be dry heat into moist heat. This can be used to your advantage if what you’re roasting is tough. You might first cook a pork shoulder roast at a low temperature covered, allowing the steamy heat to work on the connective tissue, then, when the roast is tender, uncover it and develop the exterior colour.
Try to avoid roasting in a vessel with very high sides, which prevent hot air from circulating around the food you’re cooking. My favourite vessel for roasting is an ovenproof sauté pan or a cast-iron frying pan.
I’m starting with roasted vegetables because they’re so delicious and because my sense is we don’t roast them often enough. Also, when they’re roasted, they become a bigger aspect of the meal because of the increased complexity of the flavours. Boiled cauliflower is fine, but you need a decent sauce, in my opinion, or a garnish to make it interesting. Roasted cauliflower can almost be the centerpiece of a meal the way a beef or pork roast would be.
The flavours developed in vegetables cooked at high heat are so distinct from the flavour of the same vegetables boiled that they almost ought to have different names. Roasted asparagus spears are more complex in flavour than boiled asparagus. Roasted brussels sprouts are a dream, roasted broccoli a revelation.
The only vegetables not suitable for roasting are leafy vegetables. You wouldn’t roast spinach, as it would dry out, and you wouldn’t roast kale, because it would never become tender (though you can bake this green into wholesome “chips”). All other vegetables are suitable for roasting—green and root vegetables alike. Because vegetables are almost entirely water, some care must be taken to prevent them from drying out. I like to coat most vegetables in a little oil before putting them in a hot oven. The oil also helps deliver the heat evenly over their surface. And when you’re roasting, pay attention to the moisture level. Some vegetables that you might prefer crispy, such as broccoli, and others, such as root vegetables, are best when their exterior is nicely browned but their interior is moist.
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Excerpted from Ruhlman's Twenty Copyright © 2011 by Michael Ruhlman. Photography Copyright © 2011 by Donna Turner Ruhlman. Excerpted by permission of Raincoast Books. All rights reserved.