Prepare Ingredients: Trim the green beans, slice the chicken into thin strips, and slice the onion. Mince the garlic and grate the ginger for added flavor.

Cook the Chicken: Heat 1 tablespoon of cooking oil in a large skillet or wok over medium-high heat. Add the sliced chicken, season with a pinch of salt and pepper, and stir-fry until cooked through and golden brown (about 5-6 minutes). Remove from the skillet and set aside.

Stir-Fry Vegetables: In the same skillet, add the remaining tablespoon of oil. Toss in the green beans and onion slices, stirring frequently for about 4-5 minutes, or until the green beans are bright green and slightly tender.

Combine Aromatics: Add the garlic and ginger to the skillet, stirring for 30 seconds until fragrant.

Add the Sauce: Mix the oyster sauce, soy sauce, and sesame oil in a small bowl. Pour the sauce mixture over the vegetables and toss to coat evenly. If you prefer a thicker sauce, add the cornstarch slurry and cook for 1 minute until the sauce thickens.

Return Chicken to the Pan: Add the cooked chicken back to the skillet and toss everything together until the chicken and vegetables are evenly coated with the sauce. Cook for an additional 1-2 minutes to heat through.

Finish and Serve: Sprinkle toasted sesame seeds over the stir-fry for added crunch and nutty flavor. Serve immediately with steamed rice or noodles for a complete meal.