Easy shrimp and mushroom stir fry

1 pound of jumbo prawns, peeled and deveined
1/2 cup of diced white onion
2 green onions chopped(use both green and white parts) plus more for garnish
2 cups of sliced mushroom
3 garlic cloves chopped
1 1/2-2 Tbsp of good oyster sauce(I like the Lee Kum Kee brand)
1 Tbsp of good fish sauce(I like the 3 crabs brand)
1 tsp of sugar
black pepper
1/4 tsp.salt
1 tsp of cornstarch
1 Tbsp of OMG sun dried tomato balsamic dipping oil(optional)
peanut oil

Put your prawns in a mixing bowl and add in your fish sauce, black pepper, sugar, msg(if using), and cornstarch. Mix to combine and set aside. In a hot skillet set over medium heat, pour in some peanut oil. Add in your onions, a pinch of salt, and cook until translucent. Next, add in your garlic and cook for 15 seconds(or until you can smell the garlic). Then, throw in your prawns and mushrooms and cook until the prawns turn slightly pink. Turn up the heat slightly to get a good simmer. Add in your chopped green onions and oyster sauce. Stir and cook until shrimp is done but be careful not to overcook. Taste check and adjust seasoning as needed. Turn off and remove from heat. Drizzle on 1 Tbsp of OMG sun dried tomato oil. Serve immediately with white rice.