Why It Works
- Clarified butter has a high smoke point and lends a cleaner, fuller butter flavor to Lyonnaise potatoes.
- Using sweet onion adds a mellow, yet bright flavor.
- Par-boiling potato slices first with vinegared water allows them to soften without falling apart and contributes to creamy interiors and crispy crusts when fried.
I first ate Lyonnaise potatoes, or pommes Lyonnaise―a classic French side dish made with sautéed onions and pan-fried sliced potatoes―during a month-long trip to Europe with my husband. Shortly after arriving in Lyon, we dined at a bouchon offering local specialties like salade Lyonnaise, sausage, cheese, wine (of course), and this preparation of potatoes. It's as simple as it is delicious, with its buttery-crisp potatoes, meltingly tender onions, and bright pop of fresh parsley.
The dish’s success hinges on the type of potatoes used and the technique used to cook them. Here in the United States, your best option is rich Yukon Golds. They perform much better than fluffy russets, yielding a buttery flavor, creamy interior, and slightly crisp exteriors once cooked. While russets produced the crunchiest crusts, their mild flavor couldn’t compete.
Typically, when making Lyonnaise potatoes, whole potatoes are cooked skin-on in boiling water, then sliced and pan-fried. While this works well, ensuring the potatoes cook through without becoming waterlogged and falling apart, it takes time to boil whole potatoes until tender. I wanted to find a way to reduce the cooking time without compromising the recipe's quality, so I played around with a couple different methods of cooking pre-sliced potatoes without running the risk of them losing their structural integrity.
In one test, I took the least laborious route of cooking the sliced potatoes from raw in the pan, but all that did was land me with unevenly cooked potatoes that were half-underdone and half-mush. Par-cooking indeed is essential. I then tried microwaving the potato slices to tenderize them and gelatinize their starch. It worked well, producing supple potato rounds, but they were under-seasoned (sprinkling with salt throughout the process wasn't sufficient, failing to penetrate the potato flesh, with overall bland results).
In another test, I followed Kenji’s technique for making potato hash by cooking the potatoes in salted vinegar water. Salting the water accomplished the seasoning goals well, with the potato slices properly salted through to their core. The addition of vinegar, meanwhile, acidulates the water, allowing the potatoes to tenderize while reducing their risk of falling apart (the acid strengthens the pectin that holds the potato cells together), and gives each slice a starchy outer layer that crisps up better when fried. This approach was the best, producing tender potato slices that were properly seasoned and would hold their shape for the remainder of the cooking process.
The final phase of the recipe is to fry the potatoes in more fat than you might think you need. Besides the fact that fat makes food taste good, you need a decent amount to ensure the par-cooked potatoes have thorough contact with the heat of the skillet and brown evenly. I found that using a cast iron, stainless steel, or nonstick skillet works great here. At Serious Eats, we tend to steer away from calling for nonstick but I got just as good of a crisp-brown crust with zero issues of sticking. I use clarified butter (whose water content has been removed to increase its smoke point) to infuse the potatoes with rich, clean, buttery notes; you can use regular unsalted butter in its place, just take care to adjust your heat if there’s any risk of burning the milk proteins. Searing the potatoes on both sides, coupled with resisting the urge to move them until they're fully browned, rewards you with tender, crusty, golden slices.
The dish is finished with softened browned onions, which you cook while the potatoes are simmering (I prefer sweet onions, which have a bright, mellow flavor that I prefer over yellow onion with its mildly bitter edge) and then turned out into a serving bowl and topped with fresh parsley. Paired with roasted sausage, a wedge of soft cheese, and a crusty baguette, this is traditional French fare that can be pulled off in no time.
- 1 1/2 pounds (680g) Yukon Gold potatoes (about 4 medium potatoes), peeled and cut into 1/4-inch-thick rounds
- 2 tablespoons (18g) Diamond Crystal kosher salt, plus more to taste; for table salt use half as much by volume or the same weight
- 2 tablespoons (30ml) distilled white vinegar
- 5 tablespoons (75g) melted homemade or store-bought clarified butter, divided
- 1 large sweet onion (8 ounces; 225g), thinly sliced
- Freshly ground black pepper
- Finely chopped flat-leaf parsley leaves and tender stems, for garnish
In a large pot, cover potatoes with 1 inch cold water (about 2 quarts; 1.9L). Add salt and vinegar. Bring to a boil over high heat, then reduce heat to maintain a simmer. Cook until potatoes are barely tender, offering some resistance when poked with a paring knife, about 4 minutes. Drain potatoes; set aside.
Meanwhile, in a 12-inch cast iron skillet, nonstick skillet, or stainless-steel sauté pan or skillet, heat 1 tablespoon (15g) clarified butter over medium-high heat until shimmering. Add onion, season lightly with salt, and cook, stirring occasionally, until lightly browned and softened, about 10 minutes. Add 1 tablespoon (15ml) water and scrape up browned bits on bottom of skillet. Transfer onions to a medium heatproof bowl and set aside.
Add 2 tablespoons (30g) clarified butter to now-empty skillet and heat over medium-high heat until shimmering. Add half of the drained potatoes in a single even layer and cook, without moving, until golden brown on bottom, about 3 minutes, adjusting heat as needed if at risk of scorching. Using an offset or thin metal spatula, flip potatoes and continue to cook until completely tender, offering little to no resistance when poked with a paring knife, and golden brown on second side, about 3 minutes. Transfer potatoes to bowl with onions and set aside.
Add remaining 2 tablespoons (30g) clarified butter to now-empty skillet and repeat with remaining potatoes.
Return reserved potatoes and onions to skillet, toss to combine, and cook until heated through, about 1 minute. Season with salt and pepper to taste.
Transfer pommes lyonnaise to a serving bowl, sprinkle with parsley, and serve immediately.
Make-Ahead and Storage
Pommes lyonnaise can be refrigerated in an airtight container for up to 3 days. Reheat gently in a microwave before serving.