Beef

Preheat oven to 425°F; wash and dry produce; dice potatoes into 1/2-inch pieces; trim, peel, and cut carrots on a diagonal into 1/2-inch-thick pieces; trim and thinly slice scallions separating whites from greens; finely chop garlic.
Soak bread with water and break up until pasty; stir in ground beef, scallion whites, and half the garlic; season and form into loaves; place loaves on one side of a baking sheet.
Toss carrots with a drizzle of vegetable oil, season, and spread on the empty side of the baking sheet.
Bake the sheet for 20 minutes.
Place potatoes in a pot, cover with salted water, bring to a boil, and cook until very tender; reserve 1/2 cup potato cooking liquid and drain.
Whisk together soy sauce, garlic powder, and sugar with ketchup in a small bowl to make the glaze.
Remove sheet from oven and spoon half the glaze over meatloaves; return to oven and bake 4–5 minutes more until carrots are browned, meatloaves are cooked through, and glaze is tacky.
Melt butter in the pot used for potatoes over medium heat, add the remaining garlic and cook until fragrant, add the cooked potatoes and mash, adding reserved potato cooking liquid until smooth and seasoning to taste.
Divide meatloaves, mashed potatoes, and roasted carrots between plates; sprinkle with scallion greens and serve with the remaining glaze on the side.