Cut the chicken breast into bite-sized cubes and season with half of the sea salt and black pepper.
In a medium pot, heat the olive oil over medium-high heat and sauté the chicken until browned on all sides, then remove and set aside.
Add the diced onion, carrots, and celery to the same pot, sautéing for 5 minutes until the vegetables begin to soften.
Pour in the chicken broth and add the dried thyme, bringing the mixture to a gentle boil.
Return the chicken to the pot, reduce heat to low, and let the soup simmer while you prepare the dumplings.
In a small bowl, whisk together the whole wheat flour, baking powder, and remaining salt and pepper.
Stir in the Greek yogurt and chopped fresh parsley until a soft dough forms; do not overmix.
Drop small spoonfuls of the dough onto the surface of the simmering soup.
Cover the pot tightly with a lid and steam for 10-12 minutes without lifting the lid, until the dumplings are puffed and cooked through.
Serve immediately in a deep bowl, ensuring each portion has plenty of broth and vegetables.