Savoy-Infused Mashed Potatoes with Seared Beef Medallions

1. Cook and mash the potatoes

Place the peeled and chopped Yukon gold potatoes in a large pot. Add enough water to cover them by about 2 inches (5 cm), and sprinkle in 1 teaspoon of kosher salt. Bring the water to a boil and cook the potatoes until they are tender, which should take about 10 minutes. Reserve 1 cup (250 ml) of the cooking liquid, drain the potatoes, and return them to the pot. Mash the potatoes with a fork, adding the reserved cooking liquid as needed to reach your desired consistency. Mix in 1 tablespoon of butter and season with freshly ground pepper. Set aside while you prepare the cabbage.

2. Sauté the savoy cabbage

In a large nonstick frying pan, heat 1 tablespoon of olive oil over medium heat. Add the sliced savoy cabbage, season it with salt and pepper, and sauté for about 8 minutes until it softens and starts to caramelize. Stir the sautéed cabbage into the mashed potatoes, blending well to combine the flavors.

3. Prepare the beef medallions

Freeze the tri-tip roast for about 30 minutes to make slicing easier. Once slightly frozen, cut the beef into ¼-inch (6-mm) slices, then further cut those slices into 2-inch (5-cm) lengths. Heat 1 tablespoon of olive oil in a large frying pan over medium-high heat. Cook the beef slices in a single layer, working in batches if necessary to avoid overcrowding the pan. Sear each side for about 30 seconds until just colored. Remove the beef from the pan and set aside.

4. Prepare the sauce

In the same pan, add the remaining 1 tablespoon of olive oil and reduce the heat to medium. Add the sliced shallots and cook them until they are tender and golden brown, which should take about 6 minutes. Sprinkle in the flour and stir for about 20 seconds. Gradually pour in the beef broth and vermouth, stirring constantly to prevent lumps. Allow the sauce to simmer and thicken slightly for about 6 minutes. Finish the sauce by stirring in the Dijon mustard and minced thyme. For an extra touch of richness, you can add 1 tablespoon of butter, stirring until it melts completely. Remove the pan from the heat.

5. Serve the dish

Arrange the mashed potatoes and seared beef medallions on a large platter or divide them among four plates. Drizzle the savory sauce over the beef and garnish with additional fresh thyme. Enjoy your meal!