Spray a large nonstick frying pan with cooking spray and heat over a high heat. Add the spring onions, garlic, ginger, cabbage, water chestnuts, mushrooms, red pepper and bean sprouts and stir-fry for about 8–10 minutes until the vegetables are lightly browned and softened. Transfer to a large bowl and leave to cool.
Beat the eggs with the soy sauce, chives and chilli in a bowl, season with salt and pepper and then pour into the cooled vegetable mixture. Stir to mix well.
Spray a 22 cm (8½ inch) nonstick frying pan with cooking spray and heat over a medium-high heat. Add a quarter of the egg mixture, swirl to coat the base of the pan and cook for 5–6 minutes until the underside is set. Carefully flip over and cook for 3–4 minutes until cooked. Remove and keep warm. Repeat with the remaining egg mixture.
Meanwhile, for the sauce, place the stock, tomato purée, soy sauce and hoisin sauce in a small saucepan and bring to the boil. Add the cornflour paste and cook over a high heat, stirring constantly, for 3–4 minutes until thickened. Transfer each pancake to a warmed serving plate, spoon over the sauce and serve.