Heat a large skillet or non-stick pan over medium-high heat. Once hot, add 1 tbsp oil.
Add the green beans. Leave untouched for 2 to 3 minutes, or until browned on 1 side.
Move the beans around and repeat this step until the beans are blistered and slightly wrinkly, around 10 minutes total.
Remove the beans from the pan and set aside.
Add the remaining 1 tbsp oil into the pan.
Over high heat, sauté the onion, garlic, and ginger for 1-2 minutes until cooked and aromatic.
Add in the bell pepper and sauté for 2 minutes.
Add in the mushrooms. Sauté the mushrooms for 2 to 3 minutes until tender.
Meanwhile, give the sauce a good mix again to make sure none of the starch is stuck at the bottom.
Over medium heat, pour the sauce in the pan while mixing.
Mix well to evenly coat the mushrooms.
Lower the heat as the sauce thickens.
Add back the green beans and mix well to coat in the sauce.
You can add 1 tbsp more water to thin out the sauce if you’d like. This can also help deglaze the pan. Mix well.
Taste the veggies and season with more veg oyster sauce if needed. If you're happy with how it is and the consistency of the sauce, turn off the heat.
Enjoy this with some rice or noodles. Garnish with some sesame seeds if you’d like. Enjoy while hot!