Pat the beef stew meat dry and season with a pinch of the sea salt and black pepper.
Heat olive oil in a heavy-bottomed pot over medium-high heat and sear the beef until browned on all sides, then remove and set aside.
In the same pot, add chopped carrots, celery, onion, and mushrooms, sautéing until the onions are translucent and fragrant.
Stir in the tomato paste and cook for 1 minute before pouring in the beef broth to deglaze the pan.
Return the beef to the pot, bring to a boil, then reduce heat to low and simmer, covered, for 45-60 minutes until beef is tender.
In a small bowl, whisk together the flour, baking powder, dried thyme, and the remaining sea salt.
Add water to the flour mixture and stir gently until a soft dough forms.
Drop small spoonfuls of the dough onto the surface of the simmering stew, cover tightly, and steam for 10-12 minutes until dumplings are fluffy and cooked through.