Add the beef, pork, cumin, curry powder, garlic and 2 teaspoons of the salt to a large bowl and use your hands to combine the ingredients thoroughly. Form the ground meat mixture into 2-inch balls and set aside.
Add the cubed sweet potatoes to a large stock pot and fill it with water until it is just covering the potatoes. Heat the pot on high heat until the water starts to boil and reduce it to medium-high heat. Boil the sweet potatoes until they are fork tender.
Drain the sweet potatoes from the stock pot and add them to a blender or food processor along with the ghee and remaining two teaspoons of salt. Blend on high until smooth. Set aside.
Add the avocado or coconut oil to a large frying pan or dutch oven over medium heat. Once the oil is hot add the meatballs and cook on each side for about 2 minutes until cooked through. Remove the meatballs from the pan and drain them on a paper towel and set aside. You will most likely need to cook the meatballs in 2 or 3 batches.
While the meatballs are cooking, add the coconut milk red curry paste,coconut aminos and fish sauce to a saucepan over medium-low heat and whisk to combine.
Once the meatballs have all cooked, drain the majority of the liquid and fat from the pan, leaving about 1 tablespoon in the pan. Add the red bell pepper and the onions and sauté them over medium heat for 8-10 minutes until they are softened and the onions are lightly browned.
Add the meatballs to the pan or dutch oven, pour the curry sauce over top. Stir to combine and simmer for 5 minutes.
Serve the curry meatballs and sauce over the sweet potato mash.