Prepare the Ingredients: Slice the chicken breast into thin strips, trim the green beans, and mince the garlic. If using chili, thinly slice it.

Make the Sauce: In a small bowl, whisk together fish sauce, soy sauce, oyster sauce, sugar, water, and lime juice. Set aside.

Cook the Chicken: Heat the vegetable oil in a large skillet or wok over medium-high heat. Add the chicken slices and cook for 4–5 minutes until golden and fully cooked. Remove the chicken and set aside.

Sauté the Green Beans: In the same skillet, add the green beans. Stir-fry for 3 minutes until they start to soften but remain crisp. Add the garlic and chili (if using), and stir for an additional minute.

Combine Everything: Return the cooked chicken to the skillet with the green beans. Pour the prepared sauce over the mixture. Toss well to coat evenly, cooking for 2–3 minutes to heat through.

Finish and Serve: Turn off the heat and stir in Thai basil leaves, if using. Serve immediately over steamed rice or noodles.