Preheat the oven to 450°F. Line a rimmed baking sheet with parchment paper.
Make the meatballs. In a medium bowl, place the ground beef, yogurt, green onions, ½ teaspoon o fthe chipotle chile powder, and a pinch each of salt and pepper. Using your hands, mix well until combined. Grease your hands with a bit of olive oil and roll the mixture into fifteen to twenty 2-tablespoon-size balls. Place the meatballs on the prepared baking sheet and bake until they are crisp on the outside and cooked through, about 15 minutes
Meanwhile, make the sauce. Heat the olive oil in a large skillet over medium heat. When the oil shimmers, add the onion and cook until softened, about 5 minutes. Add the garlic and ginger and cook until fragrant, about 5 minutes more. Stir in the remaining 1 teaspoon of chile powder, the curry powder, and the cinnamon and cook until fragrant, about 1 minute. Stir in the coconut milk and ½ cup of water, increase the heat to medium-high, and bring the sauce to a boil. Cook until the sauce thickens slightly, about 5 minutes. Stir in the lemon juice.
Add the meatballs and cook, stirring occasionally, until the sauce thickens further, about 5 minutes more. Remove the skillet from the heat and stir in the cilantro
Serve the meatballs and sauce with rice and naan.
Store any leftovers refrigerated in an airtight container for up to 3 days.