In a large mixing bowl, combine the ground beef, grated onion, uncooked arborio rice, chopped parsley, fresh dill, one egg, dried oregano, salt, and black pepper. Use your hands to mix gently until just combined.

Scoop out portions of the meatball mixture and roll them into golf ball-sized spheres, approximately 1.5 inches in diameter. Place on a parchment-lined tray and refrigerate for 15–20 minutes.

In a wide pot or deep skillet, pour in the chicken broth and add a drizzle of olive oil. Bring to a gentle simmer over medium heat. Carefully add the chilled meatballs and cover the pot. Simmer on low heat for 30 minutes.

In a small bowl, whisk together the eggs and the juice of two lemons until frothy. Slowly add hot broth while whisking continuously to temper the mixture.

Gently pour the tempered egg and lemon mixture back into the pot with the simmering meatballs. Stir slowly and allow the sauce to thicken over low heat for about 5 minutes.

Serve the meatballs in bowls, garnished with extra dill or lemon wedges if desired, paired with rice or fresh crusty bread.