In a large skillet, heat olive oil over medium-high heat. Add turkey and cook, stirring often until browned, 6-8 minutes.
Add whites of scallions, garlic, curry powder, coriander, cumin, and ground mustard and stir well to incorporate. Add chicken stock and season with salt and pepper.
Cook, stirring constantly until scallions are soft; 2-3 minutes. Remove from heat and let cool for 5 minutes.
Place naan bread on plate and spread 1 Tbsp. plain Greek yogurt over top. Scoop turkey mixture over top. Add more sliced scallions and diced tomatoes.
Fold into taco shape and serve.