01 - In a large bowl, combine the chicken with lemongrass, garlic, shallots, chili, fish sauce, soy sauce, brown sugar, 1 tbsp vegetable oil, and black pepper. Toss well to coat. Cover and marinate for at least 20 minutes or up to 4 hours in the refrigerator for deeper flavor.
02 - Heat 2 tbsp vegetable oil in a large skillet or wok over medium-high heat. Add the sliced onion and sauté until fragrant and translucent, about 2 minutes.
03 - Add the marinated chicken and cook, stirring frequently, until the chicken is golden brown and cooked through, about 8–10 minutes.
04 - Taste and adjust seasoning if needed. Remove from heat.
05 - Serve hot, garnished with spring onions, alongside steamed jasmine rice, cucumber slices, and lime wedges.