There’s a certain kind of dark-crusted sourdough bread I’m incapable of resisting. A sixth sense alerts me anytime I veer within a three-block radius of a bakery offering tangy country loaves with mahogany crusts. Without fail, I’ll make my way inside and buy one, even if there’s already half a loaf growing stale on my countertop.

Hello, my name is Samin, and I’m an artisanal-bread hoarder. The only way I can justify the addiction is to challenge myself to use up every bit. I’ve made endless variations of crumbs, croutons, pudding and panzanella. But the most satisfying (and efficient) use I’ve found for the glut of stale bread at my disposal is panade. If you haven’t heard of it, you’re not alone. Richard Olney, the 20th-century food writer who championed French country cooking, lamented the dish’s disappearance from cookbooks when he sang the praises of panade in The Times in 1974.

Like Olney, I believe that “the ultimate panade is the onion panade, the ancestor — and still the best — of onion soups.” We each begin by browning onions to a rich caramel color. Then we slather them over slices of dry country bread and sprinkle with generous amounts of Gruyère and Parmesan. Here, our recipes diverge: Olney carefully adds salted water, while I prefer to douse the whole thing with an absurd amount of chicken stock. Each of our versions is cooked slowly, then topped with more cheese and gratinéed. The result is sweet and savory, rich and comforting.

A triumph of upcycling, this panade is basically French onion soup without the soup — just bite after bite of cheesy, onion-and-stock-soaked bread. It’s so good I’d argue it’s worth it to buy a loaf of fancy bread right now just to let it grow stale. Then you can try the recipe. It’s also worth trying because it’s an easy way to learn a fundamental cooking lesson: Water carves a unique path — sometimes visible, sometimes not — through every recipe, whether it’s listed as an ingredient or not. Learn to identify these paths, to anticipate their twists and turns, and you’ll be better equipped to cook any ingredient, using any cooking method, with or without a recipe.

It’s easy to discount water’s importance in the kitchen. After all, it has no flavor, and more often than not it’s left off ingredient lists, making it seem like an afterthought. Yet water is an essential element of almost everything we cook and eat, and it affects the flavor and texture of all our food. This is in part because many ingredients — including all fruits and vegetables — contain some water, which they’ll start to release when they’re cut, salted and heated. And water affects how an ingredient will brown. The temperatures required for caramelization and browning almost always far exceed the boiling point of water. So the presence of water on the surface of a food, or on the bottom of a pan, is a signal that browning can’t yet occur. And in a lidded pot, steam — water’s gaseous alter ego — will condense, return to its former state and drip back inside.

Remember this when you set out to caramelize the huge pile of onions for your panade, and use it to your advantage. Slide the heap of onions into the heated oil, and add a pinch of salt, which will begin to draw water out. Give the onions a stir, release some steam and set the lid on the pan. Let the onions wilt and soften. Now that you’ve drawn the bulk of the water out of the onions, remove the lid, increase the heat and let that water cook away so that browning can commence.
Water also affects flavor in a simpler way: Add it to dilute, and remove it — or let it evaporate — to intensify flavor. When introducing his panade recipe, Olney emphasized that the precise measurements don’t matter much.

“The important thing,” he wrote, “is that there should be lots of onion, lots of bread and lots of cheese in relation to the amount of water.” Increase the proportion of liquid, and you’ll turn this dish into a less filling — but no less delicious — first course: soup. Because I’m always looking to boost flavor, I’m quick to replace water with stock, as I urge you to do with this dish. But no matter what you’re cooking, you can consider replacing water with another, more savory liquid, be it chopped canned tomatoes, coconut milk or wine, to weave in an extra strand of flavor.

And no matter the ingredient, water determines texture too. Let food absorb water — or simply retain the water it already contains — and it will be, well, moist. Cook the water out, and food will wilt or become dry, crisp or crunchy. Cook delicate proteins like eggs, fish, chicken breast and steak carefully, and they will emerge from the pan tender. Overcook them, and water will escape from within, leaving behind rubbery eggs and leathery meat. To increase the margin of error for meats that tend toward dryness, brine them before cooking to plump them with a little extra water. Starches like pasta, beans, rice and stale bread soften as they absorb water and cook.

In this panade, the drier the bread, the more liquid — and hence more flavor — it will absorb, and the more completely it will transform. As it sops up the caramelizing juices and umami-rich stock, the once-glassy crust becomes chewy, and the once-chewy crumb becomes a soft sponge for cheese and onions.
If you make better decisions about how to use water while you’re cooking, only one liquid choice will remain once you sit down to eat. As Olney advised, it ought to be among “a young dry white wine, a slightly chilled Beaujolais or an icy beer.”