Slice the chicken breast into thin, bite-sized strips and set aside.
Trim the ends of the green beans and thinly slice the red bell pepper.
In a small bowl, whisk together the tamari, minced garlic, grated ginger, toasted sesame oil, and red pepper flakes.
Heat the avocado oil in a large skillet or wok over medium-high heat until shimmering.
Add the chicken to the pan and sear until golden brown and cooked through, about 5-6 minutes, then remove chicken from the pan and set aside.
In the same pan, add the green beans and bell peppers, sautéing for 3-4 minutes until they are tender-crisp and bright.
Return the chicken to the skillet and pour the sauce over the mixture.
Toss everything together for 1-2 minutes until the sauce has thickened slightly and coated all ingredients evenly.
Serve immediately while hot and the vegetables are still vibrant.