Preheat oven to 400°F (200°C). Line a baking sheet with parchment paper.
Prepare the meatballs: In a large bowl, combine ground chicken, breadcrumbs, egg, garlic, onion, ginger, curry powder, cumin, salt, and pepper. Mix well until everything is combined.
Form meatballs: Roll the mixture into 1-inch meatballs and place them on the prepared baking sheet. Bake for 15-20 minutes, or until golden brown and cooked through.
Make the sauce: While the meatballs are baking, heat vegetable oil in a large skillet over medium heat. Saute the sliced onions for 5-7 minutes until translucent. Add the red curry paste and sauté for 1-2 minutes to release the flavors.
Add coconut milk: Pour in the coconut milk, fish sauce, lime juice, and brown sugar. Stir well to combine and let simmer for 5-7 minutes, allowing the sauce to thicken slightly.
Combine: Add the baked meatballs to the skillet with the coconut curry sauce. Stir gently to coat the meatballs in the sauce and let simmer for 5 more minutes.
Garnish the curry with chopped coriander and freeze any remaining coriander.
