This dish is based on Philippine flavours. The Philippine cuisine is a wonderful fusion of South Pacific, Spanish and Chinese influences. Vary the amount of cayenne to your own heat scale!
Combine the shrimp, 2 tbsp. of sherry and ginger in a large bowl. Cover and refrigerate for 30 minutes.
Mix the remaining 2 tbsp. of sherry, soy sauce, chicken stock, ketchup, cornstarch, rice vinegar and cayenne pepper in a small bowl.
Heat 2 tbsp. of vegetable oil in a large sauté pan over high heat. Add shrimp and stir fry until they just start to curl. Add the watercress and toss for 1 minute, just to wilt. Transfer shrimp and watercress to the serving plate.
In the same sauté pan over high heat, add the remaining 1 tbsp. of vegetable oil. Add red and yellow peppers and garlic to pan and stir fry until peppers are just slightly soft, about 1 minute. Stir sherry and vinegar mixture and add to the pan. Cook for 2 minutes or until sauce comes to a boil and sauce is clear and thick, stirring frequently. Stir in green onions. Spoon vegetables and sauce over shrimp and watercress. Sprinkle with cashews. Serve with steamed rice.