Add 2 tablespoons of oil to a large wok over medium-high heat and heat until it begins to smoke lightly. Place the pork in the pan, season with salt and pepper, and stir-fry until browned on all sides and cooked through. This will take about 3 to 4 minutes. Set it aside in a large bowl or platter.

Next, pour in 1 more tablespoon of oil, add the chicken, season with salt and pepper, and cook for 2 to 3 minutes without stirring. Then, stir-fry for 3 to 4 minutes, until well-browned and cooked through. Set it aside with the pork.

In the leftover rendered fat, add the onions, gently season with salt, and cook over low to medium heat for 10 to 12 minutes, stirring frequently, until they are browned and tender. Stir in the garlic and cook for only 30 to 45 seconds. Then, stir in the optional achiote powder and mix until well combined. Set it aside with the pork and chicken.

Add the remaining oil, turn the heat to high, and add the carrots, celery, snap peas, and cabbage. Gently season with salt, then stir-fry for 90 seconds. Set it aside with the pork, chicken, onions, and garlic.

In the wok over medium heat, add the oyster sauce, sugar, soy sauce, fish sauce, and chicken stock, and bring to a simmer.

Once simmering, add the noodles and cook, stirring constantly, until they have absorbed all the liquid and are cooked, which takes about 3 to 4 minutes.

Add the cooked meat and veggies to the wok and stir until combined.

Garnish with a squeeze of lime or lemon juice, and optionally, sliced green onions.