Shanghai Fried Noodles

Name: Shanghai Fried Noodles
Ingredients: 4 oz pork (cut into thin strips); 1 teaspoon Shaoxing wine (or dry sherry); ½ teaspoon soy sauce; ½ teaspoon cornstarch; water (for boiling); 10 oz fresh Shanghai noodles (or 2 packs Udon noodles, discard the seasoning sachets); 2 tablespoons oil; 4 oz fresh spinach (stemmed and washed); 1 scallion (cut into small rounds); 2 tablespoons soy sauce; 1 tablespoon dark soy sauce; 1 tablespoon sugar; 3 dashes white pepper; ¼ teaspoon salt (or to taste)