Freeform Chicken Meatballs with Carrots and Yogurt Sauce

1 1/2 pounds small carrots, scrubbed, tops trimmed to about 1/2", halved lengthwise
1/2 teaspoon crushed red pepper flakes
5 tablespoons extra-virgin olive oil, divided, plus more for drizzling
2 1/4 teaspoons kosher salt, divided
1 pound ground chicken or ground turkey
6 scallions, white and pale-green parts finely chopped
1 large egg, beaten to blend
2 tablespoons plain breadcrumbs
3 teaspoons finely grated lemon zest
2 teaspoons garam masala
1 cup plain Greek-style yogurt, preferably full-fat
2 tablespoons fresh lemon juice, plus more for serving
2 cups baby arugula or watercress
Flaky sea salt
 
Arrange racks in upper and lower thirds of oven; heat to 425°F.
 
Toss carrots, red pepper flakes, 2 tablespoons oil, and 1/2 teaspoon kosher salt on a rimmed baking sheet.  Roast on lower rack, tossing once halfway through, until carrots are nicely browned and fork-tender, 20–25 minutes.
 
Meanwhile, mix ground chicken, scallions, egg, breadcrumbs, lemon zest, garam masala, 2 tablespoons oil, and 1 1/2 teaspoon kosher salt in a large bowl until just combined.
 
Rub another rimmed baking sheet with 1 tablespoon oil.  Using your hands, scatter chicken mixture in small mounds (about 2") on baking sheet.  Roast on upper rack, turning pieces once halfway through with a spatula, until browned, crispy-edged, and cooked through, 15–20 minutes.
 
Meanwhile, whisk yogurt, 2 tablespoons lemon juice, and remaining 1/4 teaspoon kosher salt in a small bowl.  Spoon sauce over a platter or divide among plates, swooshing with the back of a spoon.  Transfer carrots to baking sheet with meatballs and toss to combine.  Arrange over yogurt sauce, then top with arugula.  Drizzle with oil and lemon juice; season with sea salt.
 
Serves 4.
 
From Epicurious