In a blender add the tomato, onion, and garlic and blend until smooth. Then place it in a pot and let it simmer along with the chicken broth. Make sure you do this before you do the meatballs.
For the meatballs, place the ground sirloin and ground pork in a large mixing bowl. Add the chopped carrots, tomatillo, bread crumbs, cilantro, egg whites, onion, raw rice, fresh mint, and season with salt and pepper. Mix ingredients well with your hands. Then grab your mixture and start forming the meatballs by rolling them in your hands until they have a good round shape. Make sure they’re all about the same size, that way they cook evenly.
Once you’re done rolling your meatballs, place them one by one inside the simmering sauce. Don’t drop them all at once because they might stick together. Cover them until they are cooked all the way through, normally they will take about 20-30 minutes. Add salt and pepper as needed. Serve warm and enjoy!