To begin, blend shallots, garlic, chillies, turmeric, ginger, galangal, coriander seeds, cumin, and salt into a smooth paste. Add a small splash of water if needed to help the blending. Proceed to boil the beef.

Place the beef cubes in a pot with the blended spice paste, bay leaves, kaffir lime leaves, lemongrass, and 1 litre of water. Bring to a boil, then simmer gently for 1.5 hours or until the beef is tender. Set the beef aside and reserve the stock for the sauce.

Once cooled, thread the tender beef cubes onto soaked skewers. Avoid packing too tightly so each piece grills evenly. Set aside on a tray and move to preparing the sauce base.

In a saucepan, heat the oil and sauté the remaining spice paste (if any) until fragrant. Slowly pour in the reserved beef stock while stirring. Transition to thickening the sauce.

In a small bowl, dissolve rice flour with a bit of water. Slowly whisk this mixture into the simmering sauce. Stir continuously over low heat until it thickens to a gravy like consistency. Set aside and cover to keep warm.

Preheat a grill or griddle pan. Grill the beef skewers over medium heat until lightly charred and heated through, about 2 to 3 minutes per side. Move to plating for serving.

Place 3 to 4 skewers on a plate alongside slices of lontong. Generously ladle the thick yellow sauce over the skewers and rice cakes. Garnish with fried shallots. Serve immediately while hot and fragrant.