Cook basmati rice in a large saucepan of boiling, salted water according to packet directions. Drain and return to pan. Cover and keep warm.
Meanwhile, heat oil in a wok or large frying pan and stir-fry onion for 5 minutes, until soft and golden. Add chicken and continue to stir-fry for 5 minutes, until chicken is golden.
Add curry paste and stir-fry for another minute. Stir in beans and stock and simmer on low heat for 8 minutes, until sauce thickens slightly and chicken is cooked through. Serve in bowls with rice.