Remove reedy outer layers and trim lemongrass per Note 1.

Reserve all the trimmings (for beef). Finely chop the white part (for paste.

Place Beef ingredients in a medium saucepan. Liquid should almost cover beef but not completely - if not, add water.

Add lemongrass trimmings.

Bring to boil over high heat, then reduce heat and simmer gently for 1.5 - 2 hours until beef is fork tender.

Remove beef. If there's much more than 1.5 cups liquid, simmer to reduce. Set liquid aside.

Place heavy based skillet over high heat until smoking (no oil).

Add eschalot, garlic and galangal in skillet. Get a nice char on them, then remove (~1.5 minutes).

Add dried chillies into skillet, char 10 seconds or so on each side until charred, then remove.

Once cool enough to handle: Grate galangal. Peel garlic. Break chillies in half, shake out seeds and discard.

Wipe the skillet used above or use a clean one. Heat on medium heat, add Spice Paste Dried Spices. Toast for 30 seconds or until they start to smell fragrant - do not let them burn. Immediately transfer into bowl.

Place chillies in food processor. (Note 8) Blitz until finely chopped.

Add galangal, finely chopped lemongrass, the toasted Spice Paste Dried Spices, and remaining Spice Paste ingredients, starting with 4 tbsp water. Blitz until smooth - add more water if required.

Place oil in a pot or large skillet over medium high heat. Add curry paste and cook for 3 minutes until the liquid has cooked out and it's thick and fragrant.

Add coconut milk, stir to incorporate.

Add cinnamon, star anise and reserved beef braising liquid. Reduce heat to medium and simmer for 3 minutes.

Stir in fish sauce, tamarind and sugar, stir.

Add potatoes and cook for 7 minutes or until potatoes are tender, turning as required.

Add beef and simmer for 2 minutes or until sauce has reduced and thickened.

Adjust: saltiness with fish sauce, sour with tamarind and sweet with sugar. The taste should be sweet, salty and sour, with more emphasis on the sweet and sour notes. Top up with a little water if the curry seems too thick

Serve over jasmine rice, garnished with peanuts (essential!) plus optional crispy Asian shallots and fresh chillies.