Season chicken breast pieces with Thai seasoning; set aside.
Spray a large nonstick skillet with olive oil cooking spray and heat over medium-high heat. Add seasoned chicken, onion, garlic and mushrooms. Saute until chicken is just cooked, about 8 to 10 minutes. Add the green beans, chicken stock, coconut milk and lemon zest. Bring to a boil, then reduce heat and simmer until the beans are cooked al dente, about 8 minutes, stirring occasionally. Transfer to a serving bowl and serve hot garnished with cilantro.