Cut the beef into large chunks. Place in a casserole pot and pour in enough water to cover the beef. Boil for 2 hours, or until beef is tender. Remove beef, drain and cool.
When cooled, lightly pound the meat to break up the grain. Shred the beef finely.
Dry roast the spices separately until aromatic. Coarsely grind the coriander seeds and finely grind the cumin and fennel seeds.
Blend the spice paste ingredients finely - add a little coconut milk to make sure the paste is fine. Combine the shredded beef, spice paste, ground spices and shredded leaves. Toss to mix well.
Heat the oil in a wok or casserole pot. Fry the marinated beef, stirring constantly, until it is aromatic. Pour in the coconut milk and add the tamarind slices. Cook over medium heat until gravy is thick; remove the tamarind slices, turn down the heat, and continue cooking, stirring continuously until mixture is dry. Season to taste with sugar and salt.
Continue to stir over low heat until mixture is very dry, crumbly, and has turned to floss. Remove from heat and cool completely before storing in a dry, air-tight container.