Cut the cut chicken breasts into 1-inch pieces and set aside.
Heat a large sauté pan over medium heat. Add the oil and heat through. Add the garlic and sauté until fragrant, about 30 seconds. Stir in the green curry paste and stir to combine.
Add the chicken to the pan. Cook the chicken in the curry mixture for 3 minutes, then add the green beans and sauté until they are just tender, about an additional 2 minutes.
Pour in half of coconut milk, lower the heat and simmer until the chicken is cooked through, about 10 minutes.
Add the rest of the coconut milk, fish sauce, bell pepper and bamboo shoots, stirring to combine.
Let simmer until heated through and slightly thickened, about 10 minutes. Stir half of the basil into he curry mixture.
To serve, ladle the chicken and sauce over basmati rice and garnish with the remaining basil. To add a little more heat, add Sriracha over the top (optional).
Notes
For deeper flavor, sauté the curry paste in the oil and garlic until fragrant before adding the coconut milk—this helps bloom the aromatics and creates a richer, more developed curry base.