Every cuisine on the planet figured out the same trick. Asian stir-fries pair tamarind with palm sugar. Moroccan tagines fold dried apricots into braised lamb. German cooks set sauerkraut next to pork. The contrast of sweet and sour is one of cooking’s oldest and most universal principles, and it exists because without it, flavor stays flat.
Most of us understand this instinctively when it comes to desserts or salad dressings. But what about a bowl of risotto? A pasta sauce? A side dish of roasted vegetables? In this week’s Habit Healers live, Chef Martin Oswald made the case that savory food needs sweetness too, and that the best place to find it is not in the sugar bowl. It is already sitting in your produce drawer.
The Sweetness You Never Noticed
Martin started the session with a question, “How much sugar is in a tomato?” The answer, per 100 grams of ripe tomato, is about 2.4 grams. That is roughly a quarter of a teaspoon. Not much, until you consider how that sweetness plays off the acidity of a good vinaigrette.
Then he walked through the lineup. A sweet potato comes in at about 2.8 grams of sugar per 100 grams, raw. A red bell pepper has around 4.2. Carrots sit at about 4.7. English peas are higher still. Corn tops them. And beets land at roughly 6.8 grams per 100 grams.
But the real surprise was shallots. That tiny onion, the one most home cooks use sparingly, packs about 7.9 grams of sugar per 100 grams. More than a teaspoon in a single small handful.
Now, before anyone panics about the sugar in their vegetables, Martin was quick to point out the obvious. These sugars come packaged with fiber and a range of vitamins and minerals. They are nothing like the tablespoon of refined sugar lurking in a burger bun or the sweetened dressings you get at most restaurants. The goal is not avoidance but awareness, learning to let those natural sugars do the work that refined sweeteners usually handle.
Why Roasting Changes Everything
If you bite into a raw onion, you are not going to taste sweetness. You are going to taste something sharp enough to make your eyes water. The sugar is there, but so are pungent sulfur compounds that overwhelm the palate.
Roasting changes the equation. Heat drives off water, which concentrates whatever sugar is present in the vegetable. It also triggers chemical reactions between sugars and amino acids that produce entirely new flavor compounds. The effect is dramatic. A raw sweet potato tastes starchy. A roasted sweet potato at 330 degrees for an hour tastes like dessert.
Chefs have known this for decades. Martin described how, early in his career at European health resorts, the standard approach was to steam everything. By the late 1980s and early 1990s, he and his colleagues had shifted to roasting because the flavor difference was so stark. Roasted carrots, roasted beets, roasted peppers. The produce was the same. The technique made it taste completely different.
One important note on temperature. Martin roasts at 330 to 350 degrees Fahrenheit, never higher. Going above 400 degrees risks creating acrylamide, a compound formed when starchy foods are heated to high temperatures and browned too aggressively. The goal is golden color, not dark brown. As Martin put it, go for the gold.
Two Ways to Roast Onions (and Why You Should Make a Big Batch)
Martin demonstrated two methods for turning raw onions into something sweet and deeply flavored.
The stovetop method is faster and more hands-on. Slice two onions about a quarter-inch thick, put them in a dry pan over medium heat, and let them cook for three to five minutes. When they start to stick, add a small splash of water and let that cook off. Repeat the process, adding water and letting it evaporate, until the onions turn golden.
The oven method is what Martin called the lazy version, and it is the one I am more likely to use. Slice two onions, put them in a covered pan, and roast at around 330 degrees for about 50 minutes. Then remove the cover and let them cook another 15 minutes to finish browning. Set a timer, walk away, come back to golden onions.
Either way, Martin’s strong recommendation was to cook in big batches. These roasted onions freeze beautifully and save time every night of the week. You can toss them into a bolognese, spread them on hummus toast, pile them onto a pizza, or fold them into a grain bowl. One session at the stove or oven sets you up for a week of meals.
A bonus tip from the session that had nothing to do with sweetness but earned the biggest reaction from the audience. If you refrigerate your onions overnight before cutting them, the cold suppresses the enzyme responsible for making you cry. Martin said it is not a perfect fix if you are processing 200 pounds of onions for a catering event, but for a home cook doing two or three, it makes a real difference.
The Soubise, Reinvented
The centerpiece of this week’s session was a sauce most home cooks have never heard of. A soubise is a classic French onion sauce, and in its traditional form, it starts with about a pound of butter. The butter does two things. It provides richness and it creates the smooth, creamy texture that makes the sauce cling to food.
Martin’s version skips the butter entirely. Instead, he blends roasted onions with soaked cashews, roasted garlic, and vegetable stock. The cashews, once soaked and blended smooth, provide the same creamy body that butter would, without the saturated fat. The roasted onions deliver the sweetness. The garlic adds depth. The stock adjusts the consistency.
The ingredients for this version are simple. Roasted onions (from the batch you already made), a handful of soaked cashews, a couple of cloves of roasted garlic (which you roasted right alongside the onions), vegetable stock, and whatever fresh herbs you have on hand. Martin mentioned basil and thyme as favorites, though rosemary works just as well. Blend everything until smooth, adjust the thickness with more stock if needed, and season.
Martin tasted it on camera and could not stop eating. Three bites turned into an extended sampling session, and his reaction told you everything you needed to know.
One Sauce, a Dozen Meals
What makes this soubise so practical is its versatility. Martin used it as the base for a risotto made with rye berries, though any whole grain works. Quinoa and barley are obvious substitutes, but so are buckwheat and millet. He tossed in English peas and corn for sweetness, spooned the sauce over a roasted sweet potato with sunflower seeds and a drizzle of pomegranate molasses, and kept going from there. You could stir in tomato paste for a different direction, or blend in basil puree to make something closer to a basil cream sauce. Add more cashew butter and it becomes an alfredo.
For anyone managing blood sugar, Martin offered a sensible approach. The demonstration layered several sweet elements together for visual effect, but in practice, you would choose one or two rather than stacking them all. A roasted sweet potato with the soubise is one meal. The grain risotto with peas and corn is another. And if you are watching your glucose response, eating a small salad with bitter greens like radicchio or Belgian endive before the main course can help moderate the spike.
The deeper lesson of the session was not really about any single recipe. It was about rethinking where sweetness comes from. Most of us reach for sugar or honey without considering that the vegetables already in our refrigerator have their own sweetness waiting to be unlocked. Roasting is the key. Patience is the only ingredient it requires.
If you want to get guidance on how these techniques fit your own health goals, join us in The Habit Healers community on Skool. It is where we take everything from these live sessions and put it into practice together.
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