Heat 2 tablespoons of the oil in a large frying pan on the hob and fry the beef, in batches, until lightly browned. Transfer to a casserole dish. Add the remaining oil to the pan and fry the celery and peppers until beginning to soften. Add to the dish.
Pour over the stock and add the soy sauce, ginger and chillies. Stir gently to mix. Cover with foil and place on the lower rack of the halogen oven.
Set the temperature to 200°C (392°F) and cook for 50 minutes or until the beef is tender. Blend the cornflour with the water. Stir into the beef and add the sugarsnap peas and spring onions. Cover and cook for a further 10 minutes. Serve with Thai fragrant rice.