Prepare the sauce: In a small bowl, mix fish sauce, dark soy sauce, oyster sauce, sugar, and water. Set aside.
Prep the aromatics: Finely mince the garlic and chilies. Dice the shallots. For the beans, trim the tips and cut into bite-sized pieces. Harvest only the basil leaves, discarding the tough stems.
Prepare the chicken: If using diced chicken, cut into small ½-inch cubes. If using ground chicken, ensure it's thawed and ready to cook.
Cook the chicken: Heat a large pan or wok over high heat—this ensures the chicken sears instead of steaming. Add a couple of tablespoons of oil, then toss in the diced chicken and shallots. Stir frequently, cooking for about 5 minutes, until the chicken is browned and no juices remain.
Add the aromatics: Stir in the minced garlic, bird's eye chilies, and beans. Cook for another 3 minutes. The beans should be tender with a slight crunch.
Combine with sauce: Pour the prepared sauce into the pan, tossing everything until well coated. Stir to ensure the sauce caramelizes slightly for maximum flavor.
Finish with basil: Turn off the heat and gently fold in the Thai basil leaves. The heat from the chicken will wilt them perfectly. Serve hot over rice, preferably with a fried egg!