01 - Heat olive oil in a large pot over medium heat. Add diced onion, sliced carrots, sliced celery, and minced garlic. Sauté until vegetables are softened, about 5 minutes.
02 - Stir in rinsed lentils, diced tomatoes with their juice, vegetable broth, bay leaf, dried thyme, smoked paprika, salt, and pepper. Bring to a boil, then reduce heat, cover, and simmer for 25–30 minutes until lentils are tender. Remove and discard the bay leaf.
03 - In a mixing bowl, whisk together flour, baking powder, and salt. Cut in cold diced butter using your fingertips until the mixture resembles coarse crumbs. Stir in milk until just combined — be careful not to overmix.
04 - Increase heat to bring the stew to a lively simmer. Drop spoonfuls of dumpling dough (about 1 tablespoon each) onto the surface of the simmering stew, yielding 8–10 dumplings. Cover the pot tightly and cook for 15 minutes without lifting the lid, until dumplings are puffed and cooked through.
05 - Taste the stew and adjust seasoning as needed. Sprinkle with chopped fresh parsley before serving, if desired.