Preheat oven to 140C. Generously salt the beef, then sear in neutral oil until browned on all sides. Set aside.
Blitz all Massaman spice paste ingredients in a food processor until smooth.
In the same pan, fry the paste until fragrant (about 2–3 mins), then add beef back in along with stock, coconut milk, cinnamon sticks, star anise, kaffir lime leaves, fish sauce, sugar, and tamarind and bring to a gentle simmer.
Cover and braise in the oven at 140°C and baste occasionally for 3–3.5 hours, or until the beef shreds easily with a fork.
Serve on a bed of mashed potatoes or rice, topped with fresh chilli, coriander, toasted peanuts, and a lime wedge.
