Wash and dry all produce. Adjust rack to upper position and preheat oven to 425 degrees. Trim, then thinly slice scallions, separating greens and whites. Peel carrots and sweet potatoes; cut both into 1/2-inch cubes.

Place carrots and sweet potatoes in a medium pot with enough salted water to cover by 1 inch. Bring to a boil. Cook until tender, about 20 minutes. Scoop out 1/4 cup cooking water, then drain and return cubes to pot.

Meanwhile, toss broccoli with a large drizzle of olive oil and a big pinch of salt and pepper on a baking sheet. Roast in oven until crisp and edges are tender, 15-20 minutes. While broccoli roasts, pat pork dry with a paper towel and season all over with salt, pepper, and half the paprika.

Heat a drizzle of oil in a large pan over medium-high heat. Add pork and cook to desired doneness, 5-7 minutes per side. Remove from pan and set aside on a plate to rest. Wipe out pan. Melt 1 TBSP butter in same pan over medium-low heat. Add scallion whites and cook, stirring, until just softened, about 1 minute. Whisk in stock concentrate, mustard, honey, and 1/2 cup water. Simmer until reduced, 2-4 minutes.

Reduce heat under pan to low and whisk in 2 TBSP sour cream (1 packet) and 1 TBSP butter. Remove from heat. Season gravy with salt, pepper, and remaining paprika. Set aside. Mash carrots and sweet potatoes in pot until smooth. Stir in remaining sour cream and 3 TBSP butter. Season with salt and pepper. TIP: If stiff, stir in cooking water 1-2 TBSP at a time until mash is creamy.

Divide broccoli, mash, and pork between plates. Stir any juices released by pork into gravy in pan. Spoon gravy over pork. Sprinkle everything with scallion greens and serve.