Gently twist the centre of each sausage to make cocktail sized sausages, then cut to separate. Slice the courgettes; dice the pepper, wash and slice the leek. Do not peel the apple just cut it into small pieces. Trim and slice the sweetcorn. Heat the oil in a wok or large frying pan, add the sausages and stir-fry for 5 minutes, or until browned. Add the vegetables and apple then stir-fry for a further I to 2 minutes. Season to taste. Blend the cider and cornflour together, pour into the pan and stir until the sauce has thickened and the sausages are coated. Serve with rice or pasta.