Heat the olive oil in a large pot over medium heat. Add the chopped onion and cook for 4 minutes until it softens.
Stir in the minced garlic and smoked paprika. Cook for 1 minute until the spices smell fragrant.
Add the diced potatoes, rinsed lentils, diced tomatoes, vegetable broth, and bay leaf. Stir to combine.
Bring the mixture to a boil, then reduce the heat to low. Cover and simmer for 25 minutes, stirring once or twice, until the lentils and potatoes are tender.
Remove the bay leaf. Taste and season with salt and black pepper as needed. Serve warm.