Start the marinara sauce. Place a saucepan over medium high heat. Add 1 tbsp ghee and heat until it shimmers. Add the onion and a pinch of salt, and saute, stirring frequently, until translucent, 5-6 minutes.
Add the garlic and saute, stirring continuously, until fragrant, an additional 1 minute.
Add the tomato paste, and stir until incorporated into the onions and garlic.
Add the tomatoes and the last two tablespoons of ghee and stir until the ghee is melted into the sauce. Bring to a boil, then reduce to medium low. Cover and simmer over medium low heat, stirring occasionally, until the sauce is deep red in color, 25-30 minutes. Stir in the parsley and remove from heat.
Add the chopped onion, parsley, and garlic to the bowl of a food processor. Pulse 10-15 seconds, or until the ingredients are finely minced.
Add the spices, salt, and pepper to the mixture and pulse a few times to incorporate, scraping down the sides as needed to ensure an even distribution.
Break up the turkey into small chunks and add it to the onion and herb mixture, then add the egg yolk. Pulse the mixture 8-10 times, or until the ingredients are just barely incorporated.
Roll approximately 1 heaping tablespoon of the turkey mixture into a meatball and set aside. Repeat with the remaining turkey mixture until you have approximately 18 uniformly sized meatballs. The meatballs will be very soft and moist at this stage, and you might want to lightly coat your hands with a little melted ghee or coconut oil to prevent the meat from sticking too much.
Heat a cast iron skillet over medium high heat. Add 1 tbsp ghee and heat until it shimmers. Add about a third of the meatballs to the pan. With your left hand on the handle (use an oven mitt, as the handle will get hot), and with tongs in your right hand, gently shake the pan, and flip the meatballs around with the tongs. The “jiggle” keeps the meatballs moving, and turning with the tongs helps them keep their shape. Continue to jiggle and flip until the meatballs are golden brown on all sides. Remove the browned meatballs using the tongs and set aside on a plate. Repeat with the remaining batches until all of the meatballs are browned.
Return all of the meatballs to the skillet in a single layer. Transfer to the oven and bake until the meatballs are cooked through, 15-18 minutes.
Remove the meatballs from the oven and toss in the marinara sauce. Top with additional fresh parsley, and serve immediately. These keep well in the fridge for up to 3 days, or frozen without sauce for up to two months.