Heat oil in a wok over high heat. Add garlic and chile peppers and cook until garlic starts to brown, about 30 seconds. Add pork and stir-fry until browned, about 3 minutes. Pour in dark soy sauce, sweet soy sauce, and fish sauce. Cook and stir until liquid has reduced by half, about 3 minutes.
Add chile paste, onion, and bell pepper. Stir-fry until pork is cooked through, 5 to 6 minutes. Stir in basil leaves and season with pepper. Stir until well combined.
