Step 1
Place a rack in lower third of oven; preheat to 450°. Place sweet potatoes, carrots, and scallions on a baking sheet. Drizzle a little oil over, season with salt and pepper, and toss to coat. Divide vegetables between 2 baking sheets if cramped and spread out into an even layer. Roast until tender and browned, 15–25 minutes. Step 2
Meanwhile, coarsely chop reserved carrot tops (you want about ½ cup) and place in a medium bowl. Add tomatillos, chiles, lime juice, and remaining 1 Tbsp. oil. Season salsa with salt and pepper and stir to combine (it will loosen as it sits). Step 3
Cut charred scallions into small pieces, add to salsa, and stir to combine. Divide sweet potatoes and carrots among plates and top with salsa and lots of cheese.