Place the raw beef in a large slow cooker. Add the 6 Tbsp coconut milk, water, 3 Tbsp red curry paste, fish sauce, cardamom pods, onion flakes, chilis, 1 Tbsp sweetener, cumin, coriander, cloves, nutmeg, and ginger. Cover and cook on high for about 5 hours (or low for 8). Just before serving, scoop out the meat to another dish. Then whisk into the sauce the 2 Tbsp coconut milk powder, 1 Tbsp curry paste, 2 Tbsp sweetener, and 1/4 tsp xanthan gum (if using). Break the meat into pieces and stir into the sauce, along with the chopped cashews. Garnish with chopped cilantro before serving. Recommended to serve over the Coconut Lime Cauliflower Rice for a complete meal.