For Outer Meatball Shell: 1/2 pound ground beef (not lean) 1/3 cup long-grain white rice (if you have a meat or spice grinder) or fine-grain bulgur wheat (labeled #1 or #2 in specialty Middle Eastern stores) or Cream of Rice cereal (if you don’t own a grinder) 1/2 teaspoon kosher salt
For Meatball Filling: 1/2 pound ground beef (not lean) 1/2 teaspoon ground allspice 1 teaspoon kosher salt 2 tablespoons finely chopped fresh curly-leaf parsley leaves
For Broth: Two 14.5-ounce cans (about 4 cups) low- or no-sodium beef stock 1 cup cold water 1 cup coarsely chopped celery 1 1/4 cups coarsely chopped yellow onions 1/2 cup 1/4-inch-thick carrot slices 2 teaspoons finely chopped garlic 1 tablespoon dried mint leaves Kosher salt to taste (amount will depend on how much salt is already in your beef stock) Several grindings of black pepper 1 large yellow squash or zucchini, stem discarded 1/2 cup freshly squeezed and strained lemon juice 1/2 cup fresh or frozen and defrosted peas 1 cup peeled and cubed white potatoes (any kind)
Prepare the Outer Meatball Shell 1. Combine the meat with the fine bulgur or Cream of Rice cereal and salt in a food processor and process until it becomes a smooth paste, 1 to 2 minutes. Scoop the mixture out into a small bowl using a rubber spatula. 2. Scoop out 1½ level teaspoons (½ level tablespoon) of the mixture and roll it into a smooth ball. Place it on a plate and finish rolling out the remaining balls. Set aside.
Prepare the Filling or Inner Meatballs 3. Mix the filling ingredients in a medium-size bowl by squeezing them together with your hands until very soft and well blended. 4. Scoop out 1 level teaspoon of the filling mixture and roll it into a smooth ball. Place it on a plate and continue to measure and roll into balls until the meat mixture is finished.
Form and Stuff the Meatballs 5. Take one of the shell meatballs and make an indentation with your thumb or index finger in the center to form a thin cup shape. Place one of the small filling meatballs into the cup and gently pinch together the opening with your fingertips to create a smooth, round ball. Repeat with the remaining shell and filling mixtures and set them all aside on a plate. (Note: To smooth out cracks in the shell and create a smooth meatball, dip your fingers in cold water and gently pinch the cracks together.) If any of the meatball filling is left over, roll it into small meatballs and add them to the soup along with the larger stuffed ones.
Prepare the Soup and Serve: 6. Bring the beef stock and water to a boil over high heat in a large soup pot. Reduce to a medium-low heat and drop in the meatballs. Simmer for 15 minutes. 7. Add the rest of the broth ingredients except the lemon juice, peas, and potatoes. Stir gently and simmer, uncovered, for 15 minutes. 8. Mix in the lemon juice, peas and potatoes and continue to simmer for 15 minutes. 9. Serve soup hot in a large serving bowl with squash left whole or cut into 1/4-inch-thick slices.