Adjust racks to top and middle positions and preheat oven to 425 degrees. Wash and dry produce.

Trim and halve Brussels sprouts lengthwise. Dice potatoes into ¼-inch pieces. Finely chop half the rosemary (all for 4 servings).

Toss Brussels sprouts on one side of a baking sheet with a drizzle of oil, salt, and pepper.

Toss potatoes on empty side of sheet with a large drizzle of oil, chopped rosemary, a pinch of salt, and pepper.

Roast on top rack until browned and tender, 15-20 minutes.

Meanwhile, pat pork* dry with paper towels and season all over with salt and pepper.

Heat a drizzle of oil in a large pan over medium-high heat. Add pork and cook, turning occasionally, until browned all over, 4-8 minutes. Turn off heat; transfer pork to a second baking sheet. Wipe out pan.

Roast on middle rack until pork is cooked through, 10-12 minutes. Transfer to a cutting board.

Meanwhile, roughly chop parsley.

Once veggies and pork are done roasting, combine cream sauce base, mustard, stock concentrate, 2 TBSP water (4 TBSP for 4 servings), and pepper in pan used for pork over medium-high heat.

Bring to a boil, then reduce to a simmer and cook, whisking constantly, until slightly reduced, 30-60 seconds. TIP: If sauce is too thick, add water 1 tsp at a time until sauce reaches desired consistency.

Slice pork crosswise.

Divide pork, potatoes, and Brussels sprouts between plates in separate sections. Spoon sauce over pork and potatoes and sprinkle with parsley. Serve.