Place the spice paste ingredients in a small food processor or mortar and pestle and blend into a smooth paste. If the texture is too coarse, add a splash of the measured coconut milk and blend again.
Cut the beef into 3-4 cm chunks, removing any excess fat. Place the spice paste in a deep, heavy based saucepan along with the beef, coconut milk, fish sauce, lemongrass, bay leaves and lime leaves.
Bring to a boil, then reduce to a gentle simmer and cover with a lid. Stir every 30 minutes to ensure the contents at the bottom of the pot do not burn.
After 2-2 1/2 hours, the oil from the coconut milk will split and rise to the surface. Remove the lemongrass then stir in the brown sugar.
Turn the heat up to medium high to reduce the sauce. Stir the rendang continuously until the sauce has thickened and turned deep brown. Continue stirring the beef so it absorbs the sauce and caramelizes on the outside. Taste and adjust the seasoning before serving with either fish sauce or kosher salt.
Serve with steamed rice and garnished with coconut chips.