Peel and cut potato into 1/2" dice. Bring a medium pot with potatoes and enough lightly salted water to cover to a boil. Trim bottoms off Brussels sprouts and halve (quarter if larger than a ping-pong ball). Peel and mince shallot. Pat pork tenderloin dry. On a separate cutting board, cut tenderloin into 3/4" medallions and season with 1/4 tsp. salt and 1/4 tsp. pepper.

Reduce heat of pot with potatoes to a simmer, and cook until fork-tender, 13-15 minutes. Drain in a colander and return potatoes to pot. Add 1 Tbsp. cream (reserve remaining for sauce), horseradish sauce, and a pinch of salt and pepper. Mash until desired consistency is reached. Set aside and keep warm. While potatoes simmer, roast Brussels sprouts.

Place Brussels sprouts on prepared baking sheet. Drizzle with 1 tsp. olive oil and season with 1/4 tsp. salt and a pinch of pepper. Toss to coat evenly and spread into a single layer. Roast until well-browned, 15-18 minutes. While Brussels roast, sear pork medallions.

Heat 1 tsp. olive oil in a medium non-stick pan over medium-high heat. Add pork medallions to hot pan and sear until well-browned and pork reaches a minimum internal temperature of 145 degrees, 3-4 minutes on each side. Transfer medallions to a plate. Wipe pan clean and reserve.

Return pan used to sear pork to medium-high heat and add 1 tsp. olive oil and shallot. Cook until shallot softens, 1-2 minutes. Add apple cider and thyme sprigs and reduce by half, 30-60 seconds. Add remaining cream and mustard, stir to incorporate, and bring to a simmer. Simmer until sauce is thickened, 3-4 minutes. Remove from burner and return pork medallions and any accumulated juices to pan. Flip medallions to evenly cover in sauce. Discard thyme sprigs.

Plate dish as pictured on front of card. Bon appétit!