01 - Heat olive oil in a large heavy-bottomed pot over medium heat. Add the diced onion, carrots, and celery. Sauté for 5 to 7 minutes, stirring occasionally, until the vegetables have softened and the onion turns translucent.
02 - Add the minced garlic, dried thyme, smoked paprika, and tomato paste to the pot. Stir continuously and cook for 2 minutes, allowing the spices to become fragrant and the tomato paste to darken slightly.
03 - Stir in the rinsed lentils and bay leaf. Pour in the vegetable broth and bring the mixture to a rolling boil. Once boiling, reduce the heat to low, cover the pot, and simmer for 25 to 30 minutes until the lentils are tender. Season generously with salt and pepper.
04 - While the lentils simmer, whisk together the flour, baking powder, salt, and dried herbs in a mixing bowl. Add the cubed cold butter and rub it into the flour using your fingertips until the mixture resembles coarse crumbs. Pour in the milk and stir gently just until a soft, slightly sticky dough comes together. Avoid overmixing.
05 - Remove and discard the bay leaf from the lentil mixture. Drop rounded tablespoonfuls of the dumpling dough evenly over the surface of the simmering stew, spacing them about 1 inch apart.
06 - Cover the pot tightly and cook over low heat for 15 minutes without lifting the lid. The trapped steam will cook the dumplings until they are puffed, light, and cooked through.
07 - Carefully remove the lid and check that the dumplings are firm and cooked through. Ladle the stew into warm bowls, placing dumplings on top. Finish with a sprinkle of fresh parsley and a squeeze of lemon juice if desired. Serve immediately.