Mix the ground turkey with the fennel seed, smoked paprika, oregano, garlic powder, red pepper flakes, salt and pepper.
Heat 1 tablespoon of olive oil in a large pot over medium-high heat. Add the turkey and cook for 6 to 8 minutes, breaking it into crumbles, until browned and crispy at the edges. Scoop it onto a plate.
Lower the heat to medium. Add 1 tablespoon of olive oil and the onion and cook for 4 to 5 minutes until soft. Add the garlic and red pepper flakes and stir for 1 minute.
Pour in the bone broth and scrape up the browned bits. Add the sweet potatoes, bring to a boil, then simmer for 10 to 12 minutes until just tender.
Return the turkey to the pot and stir in the kale. Simmer for 3 to 4 minutes until the kale is silky.
Whisk a ladle of hot broth into the Greek yogurt until smooth. Take the pot off the heat and stir in the yogurt mixture and lemon juice.
Taste and add salt and pepper. Ladle into bowls and top with Parmesan, chili flakes and a squeeze of lemon.