Preheat the oven to 375°F (190°C) and line a baking sheet with parchment paper.
In a mixing bowl combine ground chicken, chopped green onions, chopped cilantro, 1 tablespoon fish sauce, 1 tablespoon red curry paste, breadcrumbs, egg, 1/4 teaspoon salt, 1/4 teaspoon pepper, and sesame oil; stir gently until just combined. Do not overmix.
Form the mixture into small 1-inch meatballs and place them spaced on the prepared baking sheet.
Bake the meatballs for 18–20 minutes, until cooked through and no longer pink in the center.
While the meatballs bake, heat sesame oil (or the oil called for) in a medium saucepan or skillet over medium heat. Add 1 tablespoon red curry paste and cook, stirring, for about 1–2 minutes until fragrant.
Add the coconut milk, peanut butter, brown sugar, red pepper flakes, 1/4 teaspoon salt, and 1/4 teaspoon pepper to the pan. Stir until smooth and simmer gently for about 4–5 minutes to meld flavors.
Add the baked meatballs to the sauce and toss gently to coat them completely. Cook together briefly until heated through.
Garnish with chopped cilantro or parsley if desired and serve warm.