In a food processor, blitz the shallots, garlic, long red chillies, both turmerics, ginger, galangal and tamarind until it forms a rough paste.
Heat the vegetable oil in a large pan over a medium heat. Stir in the paste and the lemongrass and kaffir lime leaves, season with salt and pepper, and cook for 5 minutes.
Add the beef pieces and cook for 10 minutes, or until they begin to brown, stirring to make sure the meat is coated in the paste.
Stir in the coconut milk, pop on the lid, and simmer over a low heat for 1–1½ hours, or until the meat is tender and the sauce has thickened.
Serve with boiled rice and fried crispy shallots, the red chilli slices scattered over the top.