For the beef, combine the marinade ingredients in a large bowl, add the beef and stir. Cover and marinate in the fridge for 3 to 4 hours, stirring occasionally. Soak the skewers in cold water for 1 hour before using, so they don’t burn.
For the macadamia and chilli sauce, heat the oil in a small saucepan over a medium heat. Then add the garlic, fish sauce and shallots and sauté for 3 minutes. Add the coconut cream and sugar, bring to the boil then reduce to a simmer for 1 minute. Remove from the heat.
Put the macadamias, chillies, lemongrass and soy sauce in a blender or small food processor, pulse until combined then add the coconut cream mixture and pulse until well mixed.
Once the meat is marinated, thread evenly onto the skewers, making sure you leave room so you can use the stick as a handle. Heat a barbeque or grill to medium heat and cook skewers for 6-8 minutes or until beef is cooked to your liking, turning occasionally.
While the skewers are cooking, gently warm the sauce over the stove. Serve the beef skewers with the macadamia and chilli sauce, lime wedges and steamed jasmine rice.