In a large bowl, combine the ground turkey, ground beef, egg, almond flour, finely diced onion, allspice, nutmeg, salt, and pepper.
Mix gently with your hands until just combined, then roll the mixture into 12 small meatballs.
Heat the avocado oil in a large skillet over medium heat and sear the meatballs until browned on all sides, approximately 8 to 10 minutes.
Remove the meatballs from the skillet and set them aside on a plate.
Whisk the arrowroot powder into the beef bone broth until completely smooth with no lumps.
Pour the broth mixture into the skillet, scraping up any browned bits from the bottom, and simmer until the liquid begins to thicken.
Stir in the Greek yogurt until the sauce is creamy and smooth, then return the meatballs to the pan to coat them in the gravy.
Steam the green beans in a separate pot until they are tender-crisp.
Serve the meatballs and gravy alongside the steamed green beans with a dollop of tart lingonberry jam on the side.