For curry paste, drain and chop chillies, and set aside. Dry-roast spices until fragrant (30-40 seconds), cool briefly, then pound to a powder with a large mortar and pestle. Add remaining ingredients in batches and pound to a coarse paste, then combine batches and pound until smooth (you can also do this in a small food processor, adding 2 tbsp water to help process to a smooth paste).

Dry-roast bay leaves and cassia bark in a small frying pan until fragrant (20-30 seconds). Set aside.

Heat oil in an extra-large saucepan over medium-high heat, add beef in batches and brown all over (1-2 minutes each side). Transfer to a plate, rinse pan out, then return to medium-high heat, add half the coconut cream and cook, stirring occasionally, until it cracks and the fat separates (4-5 minutes). Add curry paste, bay leaves and cassia bark, and stir-fry until fragrant and curry paste is toasted (1-2 minutes; this may take longer if water has been added to make the paste). Add coconut milk, remaining coconut cream and 250ml water and bring to a simmer. Return beef to pan, reduce heat to low-medium and simmer uncovered until beef is tender and sauce reduces to just cover beef (3½-4 hours; if sauce reduces too much, add a little more water half a cup at a time to keep beef just covered without diluting the sauce too much). Add potato and simmer until beef is very tender and potatoes are soft (20-30 minutes). Season curry to taste with palm sugar, fish sauce and tamarind in the last few minutes of cooking for a balance of salty, sweet and sour.

Meanwhile, for fried shallots, heat oil in a wok over medium heat to 180C or until it shimmers. Add shallots and fry, stirring occasionally, until golden and crisp (1-2 minutes). Remove with a slotted spoon and drain on paper towels.

Scatter curry with coriander, julienned ginger and fried shallots, and serve with steamed jasmine rice.