Step 1: In a large bowl, combine ground chicken, 2 cloves minced garlic, 1 tablespoon grated ginger, 2 tablespoons chopped cilantro, breadcrumbs, egg, salt, and pepper. Gently mix with your hands until just combined.
Step 2: Roll the mixture into approximately 1-inch meatballs. You should get about 20-24 meatballs.
Step 3: Heat 1 tablespoon of olive oil in a large skillet or Dutch oven over medium-high heat. Add meatballs in batches and sear for 3-4 minutes, turning occasionally, until browned on all sides. Remove browned meatballs and set aside.
Step 4: In the same skillet, reduce heat to medium. Add the remaining 1 tablespoon of olive oil (if needed). Add diced onion and cook, stirring occasionally, until softened and translucent, about 5-7 minutes.
Step 5: Stir in the red curry paste, 2 cloves minced garlic, and 1 tablespoon grated ginger. Cook for 1-2 minutes, stirring constantly, until fragrant.
Step 6: Pour in the full-fat coconut milk and chicken broth. Add the fish sauce, brown sugar, and lime juice. Stir well to combine, scraping up any browned bits from the bottom of the pan. Bring the sauce to a gentle simmer.
Step 7: Carefully return the browned chicken curry meatballs to the skillet, nestling them into the simmering sauce. Reduce heat to low, cover, and let simmer for 15-20 minutes, or until meatballs are cooked through and the sauce has slightly thickened.
Step 8: Uncover the skillet. If the sauce is too thin, simmer for an additional 5-10 minutes, stirring occasionally, until it reaches your desired consistency.
Step 9: Taste and adjust seasonings as needed. You might want a pinch more salt, a squeeze of lime, or a dash more fish sauce to balance the flavors.
Step 10: Garnish with fresh cilantro and a sprinkle of red pepper flakes (if using) before serving. Serve hot over rice, noodles, or with naan bread.