Heat the olive oil in a large pot over medium heat. Add the onion and cook until it softens, about five minutes.
Stir in the garlic and smoked paprika. Cook for one minute until the mixture smells fragrant.
Add the celery root and parsnips. Stir everything so the vegetables pick up the paprika.
Pour in the lentils, vegetable broth, salt, pepper, and bay leaves.
Bring the pot to a boil, then lower the heat and simmer uncovered for 30 minutes until the lentils are tender.
Remove the bay leaves. Ladle the stew into bowls and top each serving with fresh parsley.