Adjust rack to top position (middle and top positions for 4 servings) and preheat oven to 425 degrees. Wash and dry all produce. • Dice potatoes into ½-inch pieces. (TIP: For a smoother texture, peel potatoes first.) Strip thyme leaves from stems until you have 1 tsp (2 tsp for 4); mince leaves. Reserve remaining thyme sprigs for the next step. Trim and thinly slice scallions, separating whites from greens; mince whites. Trim green beans if necessary. Halve, peel, and thinly slice onion. Peel and mince garlic.

Place potatoes and reserved thyme sprigs in a medium pot with enough salted water to cover by 2 inches. Bring to a boil; cook until tender, 15-20 minutes. • Reserve ½ cup potato cooking liquid, then drain and return potatoes to pot; remove and discard thyme sprigs. Mash with sour cream and 1 TBSP butter (2 TBSP for 4 servings) until smooth, adding splashes of reserved potato cooking liquid as needed. • Season with salt and pepper. Keep covered off heat until ready to serve.

While potatoes cook, in a medium bowl, combine beef*, panko, scallion whites, half the Fry Seasoning (you’ll use the rest later), 1 TBSP water (2 TBSP for 4 servings), ¾ tsp salt (1½ tsp for 4), and a pinch of pepper. • Form into 10-12 (20-24 for 4) 1½-inch meatballs.

Place meatballs on one side of a lightly oiled baking sheet. Toss green beans on empty side with a drizzle of oil, salt, and pepper. • Roast on top rack until meatballs are cooked through and green beans are browned and tender, 14-16 minutes. (For 4 servings, divide between 2 sheets; roast meatballs on middle rack and green beans on top rack.)

Meanwhile, melt 1 TBSP butter (2 TBSP for 4 servings) in a large pan over medium-high heat. Add onion; cook, stirring, until softened, 7-9 minutes. Stir in garlic and minced thyme; cook until fragrant, 30 seconds. • Add a drizzle of oil, half the flour (all for 4), and remaining Fry Seasoning; cook, stirring, until lightly browned, 1-2 minutes. • Whisk in ¾ cup water (1½ cups for 4) and stock concentrate. Bring to a simmer, whisking, until thickened, 2-4 minutes. • Reduce heat to low; stir in another 1 TBSP butter until melted.

Season gravy with salt and pepper. Add meatballs and stir to coat. (TIP: If gravy seems too thick, stir in a splash of water.) Turn off heat. • Divide mashed potatoes between plates; top with meatballs and gravy. Add green beans to the side. Garnish with scallion greens and serve.