Gingered Pork on Watercress

Ingredients

• A bunch of watercress
• ½ lb (230 g) pork fillet
• 1½ teaspoons minced ginger
• ½ lb (230 g) potatoes
• Salt and black pepper
• 2 teaspoons sesame seeds
• 1 large egg
• 2 teaspoons sesame oil
• 2 tablespoons vegetable oil
• ½ teaspoon cornstarch
• 3 tablespoons dry sherry
• 1 tablespoon soy sauce