Quarter the potatoes and place in a large pot with a large pinch of salt and enough water to cover. Bring to a boil and cook for about 12 minutes, or until easily pierced them with a knife. Drain and set aside.

Finely chop the tarragon leaves. Trim, halve, and thinly slice the Brussels sprouts into shreds. Slice the pork tenderloin into 1-inch thick medallions.

Heat 1/2 tablespoon oil in a large pan over medium-high heat. Add the Brussels sprouts and cook for 4 minutes, tossing constantly, until soft and slightly crispy. Set aside and cover to keep warm.

In the same pan, heat another 1/2 tablespoon oil over medium heat. Season the pork with salt and pepper. Sear the medallions for a 2-3 minutes per side, until browned and cooked to desired doneness. Set aside.

Add the stock concentrate, tarragon, and 1/2 cup water to the pan. Simmer for 2-3 minutes, until reduced and slightly thickened.

Remove pan from heat and stir in the sour cream. Season with salt and pepper.

Serve the potatoes and brussels sprouts with the pork medallions on top. Drizzle with the tarragon cream sauce and enjoy!