Mix the meatball base. In a large bowl, combine ground turkey, breadcrumbs, egg, onion, garlic, parsley, salt, pepper, allspice, and nutmeg. Use clean hands or a fork to mix until just combined. Don’t overmix or the meatballs can get tough.
Shape the meatballs. Scoop into 1 to 1.5-inch balls (about 24–28 meatballs).
Lightly oil your hands if the mixture is sticky.
Brown the meatballs. Heat 1–2 tablespoons olive oil in a large skillet over medium heat. Sear meatballs in batches until browned on at least two sides, about 5–7 minutes total. Transfer to a plate.
They don’t need to be fully cooked yet.
Make the roux. In the same skillet, add 2 tablespoons oil or light butter. Whisk in the flour and cook 1–2 minutes until lightly golden. Scrape up browned bits—those are flavor.
Build the sauce. Slowly whisk in the broth, a little at a time, to avoid lumps.
Bring to a gentle simmer. Stir in Dijon and Worcestershire. Season with salt and pepper.
Simmer the meatballs. Return meatballs and any juices to the skillet.
Cover and simmer on low for 8–10 minutes, or until the centers reach 165°F (74°C).
Finish with yogurt. Turn heat to low. Whisk the Greek yogurt in a small bowl with a ladle of hot sauce to temper it, then stir it back into the pan. Simmer 1–2 more minutes.
Adjust seasoning.
Serve. Spoon over noodles or mash. Garnish with parsley. If you enjoy sweet-tart contrast, add a small dollop of lingonberry jam on the side.