From America's Test Kitchen Season 10: Making Meat and Potatoes for Company
Originally conceived as a way to use up leftover boiled potatoes, potatoes Lyonnaise came to represent the best of classic French bistro cuisine: buttery, browned potato slices with strands of sweet, caramelized onion and fresh parsley—a simple yet complex skillet potato dish. Sadly, many versions are greasy and heavy rather than rich and complex. We wanted a return to the original elegant, buttery potato and onion dish—but one that didn’t require leftover potatoes to make.
First, we had to choose the right potato. Yukon Golds beat out high-starch russets and low-starch Red Bliss. We precooked the potatoes in the microwave so that, once added to the skillet, they would cook through in the time they took to brown (without the microwave, the potatoes charred on the outside before cooking through). While the potatoes were in the microwave, we cooked the onions just long enough to release moisture and cook in their own juices. To finish the dish, we united the onions and potatoes in a brief sauté for the perfect melding of flavors. A sprinkling of minced parsley gave the dish a fresh taste and bright color.
The finished potatoes should have a smooth and slightly elastic texture. White cheddar can be substituted for the Gruyère. For richer, stretchier aligot, double the mozzarella.