Combi Oven: The Best New Chef Tool
Star chefs like Daniel Boulud swear by the amazing cooking powers of combi ovens, but the price has shut most home cooks out—until now. F&W's Daniel Gritzer looks at how new, more affordable options can revolutionize our kitchens.
I never really questioned the adequacy of my oven. As long as it got hot, I pretty much figured it was doing its job. But as more and more chefs are upgrading their kitchens with a professional "combi" oven, a steam and convection oven rolled into one, I've started to feel like my home model is as up-to-date as a telegraph in a world of smartphones.
Unlike standard ovens, combi ovens offer the ability to regulate humidity along an impressively wide temperature range (many models can go lower than 100 degrees and higher than 500). That makes combis the Swiss Army knives of ovens, with a staggering range of capabilities: They can brown a roast with high, bone-dry heat or cook rice with the steam on full blast (there's no risk of the rice scorching as it can on a stove top). They can dehydrate fruit when set to a very low temperature and zero moisture, or keep dough perfectly supple during proofing—same low temperature, but with added humidity.
In the past, only a few wall-mounted models have been available for the home cook, some costing upward of $8,000—which helps explain why combi ovens haven't really caught on outside professional kitchens. But recently, I learned of Cuisinart's CSO-300 "combo" countertop oven, a $300 newcomer to the combi market. My first shot at trying one out, I immediately place an order.
While I wait for my oven to arrive, I turn to the combi chapter in Modernist Cuisine, the 2011 opus on the science of food and cooking. But its discussions of dew points, relative humidity and wet-bulb versus dry-bulb temperatures lose me in a thermodynamic fog. For help, I call Scott Heimendinger, Modernist Cuisine's director of applied research.
As Heimendinger explains it, humidity has a profound effect on how food cooks. "Water molecules conduct heat much faster than air," he says, explaining that it's the same phenomenon that causes hot, humid weather to feel more oppressive than hot, dry weather. Not only does humid air transfer heat more efficiently to food, cooking it more quickly, it also helps prevent the water in the food from evaporating, keeping the moisture locked inside. "In the heat of a traditional oven, you dry out the exterior of your food before the interior," he says. That can be a good thing when you want a deeply browned crust on a prime rib, but it can be a problem with foods like potatoes, which is why you typically wrap them in foil before baking to capture the steam. (The steam function of a combi oven re-creates that effect.)
At chef Daniel Boulud's New York City flagship restaurant, Daniel, the kitchen is equipped with two Rational brand commercial combis; I set up an appointment for a demo. When I arrive, chef de cuisine Eddy Leroux is using one of the combis to steam a silicone tray filled with tiny domes of eggplant custard. The combi oven, he says, allows him to cook egg-based dishes without the standard hot-water bath. Sitting nearby is a tray loaded with deep-red dried-sumac bobs, berry clusters to be ground into a tart spice. "Every year, our forager brings us 40 pounds of fresh sumac, and I dehydrate it myself in the combi," Leroux tells me. We taste this latest batch, so fresh it leans more toward fruit than spice.
Boulud soon joins us and begins raving about all the things a combi oven can do. He tells me it's great not just for proofing bread but also for baking it, since the combi can deliver the initial blast of steam that is essential for a good crust. "It's so versatile, you can wash and dry your dog in it," he jokes. In fact, he's such a fan that when he renovated the home kitchen in his apartment above the restaurant last winter, he decided to install Gaggenau's high-end home combi unit ($7,300), which is hard-lined into the water supply. "My old kitchen had two American-style ovens," he says. "One I used for storing pots and pans, the other for soda cans and bottled water—I was ready for something more serious."
Back in the F&W Test Kitchen, I unpack my newly arrived CSO-300. It looks more like an oversize toaster oven than a high-tech cooking toy. I quickly realize that there's a bit of a learning curve to get the most out of it: Adding steam while cooking may sound simple, but it feels like I've just discovered a new dimension. Roasting a chicken typically comes down to choosing between high or low heat, something experienced cooks rarely agree on. But using a combi oven also requires deciding whether to opt for humidity or not. I go with the CSO-300's "bake steam" setting, which adds humidity but not full-on steam, and set the temperature to 450 degrees. The chicken cooks in about 20 minutes, so fast my colleagues demand proof that it isn't raw before they'll eat it. We all agree it is the juiciest roast chicken meat we've ever had, but the skin isn't brown enough. Dry heat, it turns out, would have been a better option.
Heimendinger had suggested I try cooking steak at a low temperature with high humidity, a fabulous trick that mimics sous vide. I set a rib eye to gently cook in a dense cloud of water vapor at exactly 120 degrees, then leave it unattended while I go to a meeting. When I return 40 minutes later, a thermometer shows the meat is exactly 120 all the way through—just shy of medium-rare. I take it out, pat it dry and toss it into a smoking-hot skillet to quickly sear both sides. The result is a beautifully pink, tender steak, which makes me think what a great solution a combi can be for timing-challenged folks at home: Instead of fretting about when to start cooking something like a steak, they can just throw it in a combi, make the rest of the meal while the meat slowly comes up to temperature, and then sear it in the pan right before eating.
After my steak success, I try bread in my "Easy-Bake" oven, as I've started affectionately calling the little CSO-300, and produce a loaf with one of the best homemade crusts I've ever seen. Obsessed with the combi's potential for cooking eggs, I next poach several ramekins of the most delicate chawan mushi (savory Japanese egg custard) imaginable, then take advantage of the combi's drying power to dehydrate green olives. For a $300 countertop appliance, this thing is pretty fierce.
Even so, I am excited to report that the price of wall combis is starting to come down as more appliance companies enter the market. Miele's new model costs $3,495; Jenn-Air's, about $2,800; and Wolf is releasing new ones in two sizes, 24-inch and 30-inch (starting at $3,850). As a renter, it may be a while before I can replace my home oven with something—as Boulud says—a bit more serious. In the meantime, I have some roast chicken to perfect.