Bring a large pot of water to a boil and add in the green beans. Cook for 2 minutes then drain and cool the green beans in ice water. Once cooled drain and set aside.
In a small bowl combine the sauce ingredients (water, rice vinegar, hoisin, soy sauce, honey, cornstarch and sesame oil), mix well. Set aside.
In a large skillet over medium high heat add the olive oil, once hot add in the pork, season with salt, pepper and garlic powder. Cook the meat until fully cooked and browned. Add in the mushrooms and gochugaru. Sauté for 5 minutes or until the mushrooms are done. Remove from the pan and set aside.
Turn the heat down to medium, add the butter to the pan. Once melted add in the green beans, ginger, garlic and green onions. Sauté for 1 minute.
Pour in the sauce mixture and bring to a simmer. Simmer and stir, until thickened.
Add the pork and mushrooms back to the pan, stir until well combined. Garnish with sesame seeds and sliced green onions.
Serve with steamed rice. Enjoy!