Cook the beans in a large saucepan of boiling water for 5 minutes. Drain, then refresh in a sieve under cold running water to stop the cooking process. Drain again.
Heat the oil in a large frying pan. Add the shallots, garlic, celery, carrots and capsicum. Cook over a high heat for about 3 minutes, stirring well until the vegetables are just starting to soften.
Sprinkle the curry powder into the pan over the vegetables, stir to coat, cook for 1 minute, then add the beans and zucchini. Stir again.
Mix together the cornflour paste and stock, then pour the mixture into the pan. Bring to the boil, then reduce the heat, cover with a lid and simmer for 5–8 minutes until the vegetables are tender and the sauce has thickened. Season to taste with salt and freshly ground black pepper, then serve immediately, garnished with a sprig of fresh parsley or coriander.