Heat a large wok or heavy skillet over high heat. When it's very hot, add the oil. When the oil is hot, add the seitan, curry, garlic, ginger and chilli
paste. Stir-fry for 1-2 minutes, then add the green pepper and mushrooms and onion. Stir-fry for another 2 minutes.
Add the broth, soy sauce and sherry. Cover, turn the heat down to medium low and simmer for 10 minutes. Stir in the dissolved cornstarch, turn the heat up to high and stir until it has thickened.
Serve with steamed rice.