We love our stuffed koosa squash cooked in tomato broth--consider this Koosa Soup with Meatballs an easier, faster way to all of those flavors we love in a beautiful, warming bowl of soup. If reheating the soup from the refrigerator, add water to loosen the broth, and more salt if needed.
In a large, heavy soup pot, heat the olive oil over medium heat. Add the onion, celery, and 1/2 teaspoon of the salt. Stir to combine, then saute until soft, about 5 minutes.
Cut the koosa into small wedges. Trim the squash by cutting off the ends. Cut the squash lengthwise into quarters, then cut into 1/2-inch wedges. Add the koosa, garlic, cinnamon, and rice to the pot, season with 1/2 teaspoon salt, stir, and cook just until the koosa is softened, another 5 minutes.
Add the tomato juice and 2 cups of water, along with 1/2 teaspoon salt, increase the heat and bring the soup to a boil. Reduce the heat to low and simmer until the rice is cooked through, about 20 minutes.
Meanwhile, make the little meatballs. In a medium bowl, combine the beef or lamb, bulgur, garlic, cinnamon, salt, and mint. Shape the meat into small, 1-inch meatballs (makes about 50 meatballs).
Add the meatballs to the pot, increase the heat and bring to a boil. Reduce the heat to medium and cook until the meatballs are cooked through, about 15 minutes.
Add the remaining teaspoon of salt and lemon juice. Taste and adjust seasoning, if needed. Serve in warmed soup bowls, with a dusting of the chopped mint and a dollop of labneh on top of each.