Siu Mai (Open-Face Pork and Shrimp Dumplings)

Ingredients

• 6 whole leaves plus 1 packed cup finely chopped napa cabbage
• 24 frozen peas, thawed
• 1 tsp. plus 1 tbsp. cornstarch
• 3⁄4 tsp. salt
• 3⁄4 lb. ground pork
• 2 Tbsp. shaoxing jiu (Chinese rice wine)
• 2 Tbsp. soy sauce
• 1 1⁄2 tbsp. sesame oil
• 1 Tbsp. finely chopped ginger
• 1⁄4 tsp. sugar
• 5 medium shelled deveined shrimp (about 2 oz.), finely chopped
• 4 canned drained water chestnuts, finely chopped
• 1 scallion, finely chopped
• Pinch of freshly ground black pepper
• 24 round thin 3 1⁄2" Hong Kong-style dumpling wrappers