In a small bowl, add the miso, soy sauce, sugar, garlic, and sesame oil. Stir until well combined.
Cut the root section of the bunch of mushrooms off, about 1.5 inches from the roots. Use your fingers to carefully pull away sections of the mushrooms into smaller sections.
In a medium frying pan, add 1 cup of water. Bring to a boil and then add the mushrooms. Blanch mushrooms for about 1 minute. Drain off the water and set mushrooms aside.
In the same pan on medium heat, add the sauce. Stir continuously for 20-30 seconds. Add the mushrooms and turn the heat down to medium low. Carefully stir the mushrooms around so it gets coated in the sauce. Cook for 2 minutes. Remove from heat and top with sliced green onions and sesame seeds. Serve with rice. Enjoy!