Line a 33 x 46 cm / 13 x 18 inch rimmed baking sheet with parchment. In a 2.8 L / 3-quart bowl, mix the turkey, certified gluten-free rolled oats, egg, Parmesan, parsley, 2 cloves minced garlic, Italian seasoning, 3/4 tsp salt, pepper and 2 tbsp water with a fork until just combined. Stop once no dry oats show, because overmixing makes the meatballs tough.

With wet hands, roll the mixture into about 22 meatballs, 1 heaping tablespoon (about 30 g) each, and set them on the baking sheet. Keep them in the fridge while you start the soup.

Heat the olive oil in a 5.5-quart / 5.2 L Dutch oven (26 cm / 10-inch wide) over medium heat. Add the onion, carrots and celery and cook for 6 minutes, stirring often, until the onion turns soft and translucent. Add the 3 cloves garlic and cook for 30 seconds until fragrant.

Pour in the gluten-free low-sodium chicken broth and water, then add the rice, bay leaf and thyme. Bring to a boil over high heat, reduce to a gentle simmer with small bubbles, and cook for 6 minutes.

Lower the meatballs into the pot one at a time with a spoon. Don't stir for the first 3 minutes so the outsides can set. Simmer gently for 12 minutes total, until the meatballs are firm and pale with no pink inside, the center reads 165 F / 74 C, and the rice is tender.

Stir in the spinach and cook for 2 minutes until wilted. Remove the bay leaf, stir in the lemon juice, and taste for salt and pepper. Ladle into bowls while hot.