Adjust rack to top position and preheat oven to 425 degrees. Bring 3 TBSP butter (6 TBSP for 4 servings) to room temperature. Wash and dry produce.

Peel and dice sweet potatoes into ½-inch pieces. Place in a medium pot with enough salted water to cover by 2 inches. Bring to a boil and cook until tender, 15-20 minutes.

Drain and return sweet potatoes to pot.

Keep covered off heat until ready to mash.

While sweet potatoes cook, trim and halve Brussels sprouts lengthwise. Toss on a baking sheet with a drizzle of oil, salt, and pepper.

Roast on top rack until golden brown and tender, 18-22 minutes.

Meanwhile, thinly slice chives. Place peppercorns in a zip-close bag and crush with a heavy-bottomed pan or rolling pin; pour onto a plate and spread into an even layer.

Pat beef* dry with paper towels; season all over with salt. Press both sides of beef into crushed peppercorns to evenly coat. TIP: For a milder flavor, sprinkle beef with peppercorns instead.

Heat a drizzle of oil in a large pan over medium-high heat. Add beef and cook almost to desired doneness, 4-7 minutes per side.

Add stock concentrate and 2 TBSP water (3 TBSP for 4 servings). Simmer until sauce has thickened and beef reaches desired doneness, 1-2 minutes more. Turn beef to coat, then transfer everything to a shallow dish.

Mash drained sweet potatoes until smooth. (TIP: If sweet potatoes have cooled, mash over medium-low heat.) Stir in sour cream and 1 TBSP softened butter (2 TBSP for 4 servings) until combined. Season generously with salt and pepper.

In a small microwave-safe bowl, combine remaining 2 TBSP softened butter (4 TBSP for 4 servings), 1 tsp chives (2 tsp for 4), salt, and pepper. TIP: If butter is still cold, microwave 5-10 seconds.

Divide beef, sweet potatoes, and Brussels sprouts between plates. Sprinkle Brussels sprouts with almonds. Top beef with chive butter. Garnish with remaining chives and serve.