Shell And Devein the shrimp. In a bowl toss the shrimp with salt; let sit for 5 minutes. Rinse thoroughly with cold water, drain and pat dry; set aside. Cut the asparagus diagonally into 2-inch lengths. Bring a large pot of water to a boil. Drop the asparagus into the water and blanch for a few seconds or until it turns bright green. Remove and shower with cold water to stop the cooking. If using canned mushrooms, drain and rinse them with cold water; set aside. Cut the green onions, including part of the green tops, into 1 1/2-inch lengths. Heat a wok over medium-high heat. When hot add the oil and garlic; toss until lightly brown. Turn the heat to high and add the green onions and shrimp to the wok; stir-fry together until the shrimp turn bright orange and feel firm to the touch, about 30 seconds to a minute. Add the asparagus, mushrooms, sugar, pepper, fish sauce, oyster sauce and chicken stock; stir-fry together until the mixture is heated through and sauce has a light cream consistency. This should take no more than a few seconds.