In a bowl, combine the hoisin sauce, vinegar and soy sauce. Set aside.
Pat the shrimp dry with paper towels.
In a wok, heat half the vegetable oil over high heat. Stir-fry half the shrimp until they change colour, about 2 minutes. Season with salt. Set aside and repeat with the remaining vegetable oil and shrimp. Set aside.
In the same wok over medium-high heat, stir-fry the remaining ingredients, except the green part of the green onions, in the sesame oil for 3 to 4 minutes. Add the shrimp and reserved sauce. Stir-fry for 1 to 2 minutes more. Garnish with the green part of the green onions.