Shrimp with Napa Cabbage and Ginger

Name: Shrimp with Napa Cabbage and Ginger
Ingredients: 1 bunch scallions; 1 lb large shrimp in shell (16 to 20 per lb), peeled and deveined; 2 tablespoons medium-dry Sherry; 1 teaspoon cornstarch; 1/4 teaspoon white pepper; 1 teaspoon salt; 1 (2-lb) head Napa cabbage, quartered lengthwise, cored, and cut crosswise into 1 1/2-inch pieces (10 cups); 3 tablespoons vegetable oil; 1 teaspoon minced peeled fresh ginger; 1 red bell pepper, cut into 1/4-inch-wide strips (1 cup); 1 tablespoon soy sauce; Accompaniment: cooked rice