Cook the Pork: Heat a wok over medium-high heat and add enough neutral oil to coat the bottom. Once shimmering, season pork with salt and pepper, then stir-fry for 3-4 minutes until browned. Remove from the pan, keeping juices.

Sear the Chicken: In the same wok, add another tablespoon of oil if needed and raise to high. Sear chicken thighs for 5-7 minutes until golden and cooked. Transfer to the same plate as the pork.

Sauté Aromatics: Lower the heat to medium, toss in diced onion with salt, and stir for 10-12 minutes until golden. Add minced garlic and achiote powder, sauté for another 30-45 seconds. Set aside.

Stir-Fry Vegetables: Increase heat to high, add remaining oil, and stir-fry carrots, celery, snap peas, and cabbage for 90 seconds until vibrant. Transfer to the side with chicken and pork.

Prepare the Sauce: In the same wok, pour in oyster sauce, sugar, soy sauce, fish sauce (if using), and chicken stock. Simmer over medium heat, stirring occasionally until slightly thickened.

Cook Noodles: Add soaked vermicelli noodles to the simmering sauce. Stir gently for 3-4 minutes until tender, adding more chicken stock if noodles look dry.

Combine: Reduce heat to low, add cooked meats and sautéed vegetables back to the wok. Toss gently for 2-3 minutes until heated through.

Serve: Remove from heat and finish with a squeeze of fresh lemon or lime juice. Garnish with chopped green onions and serve hot.