Blanch the beans in boiling salted water until slightly crunchy. Refresh in cold water and set aside.
Pour 3 tbsps hot water over the tamarind pulp and leave to soak for 5 minutes. Rub the pulp with your fingers then strain into a bowl. Add the lime juice, fish sauce and palm sugar.
Place a wok ( or large frying pan) over a high heat then add the oil. When it is sizzling hot add the lime leaves, garlic and chilli and stir.
Add the beans and stir fry for a few minutes before adding the beef . Once the beef has browned add in the tamarind liquid and simmer for 1-2 minutes.