Put the prepared green beans into a large microwave-safe bowl and cover with plastic wrap.
Microwave the beans on half power for 3 - 3½ minutes. Carefully uncover and set aside.
In a small bowl, whisk together the teriyaki sauce, miso paste, and sesame oil. Set aside.
Heat a large skillet over very high heat.
Add the grapeseed oil to the skillet along with the prepared pre-cooked green beans.
Allow the beans to cook and blister (do NOT stir) for approximately 2½ - 3 minutes.
Stir gently and add the black pepper to the skillet.
Allow the beans to cook for an additional 2-3 minutes.
Reduce the heat to medium and add the miso sauce to the skillet.
Stir well to coat the beans with the sauce.
Cook for 1 - 2 minutes to heat through.
Sprinkle the beans with sesame seeds and spoon into a serving bowl.