Prepare the Aromatics: Heat the olive oil in a large pot over medium heat. Add the finely diced onion and cook until softened and translucent, about 5 minutes. Add the minced garlic and cook for another minute until fragrant.
Toast the Spices: Add both the sweet and smoked paprika to the pot. Stir constantly for 30 seconds until the spices are fragrant, being careful not to burn them.
Build the Soup Base: Add the diced carrots and cubed potatoes to the pot. Stir to coat them in the onion and spice mixture. Pour in the vegetable broth and add the rinsed mountain lentils and the bay leaf.
Simmer: Bring the soup to a boil, then reduce the heat to low, cover, and let it simmer for 25-30 minutes, or until the lentils and potatoes are tender.
Prepare the Tofu: While the soup is simmering, finely dice the smoked tofu. In the last 5 minutes of cooking, stir the diced tofu into the soup to heat through.
Final Touches: Remove the bay leaf. For a slightly creamier texture, use an immersion blender to briefly pulse the soup 2-3 times, leaving most of the chunks intact. Alternatively, you can mash a few potatoes and lentils against the side of the pot with a spoon.
Finish and Season: Turn off the heat. Stir in the 3 tablespoons of vegan sour cream until fully incorporated. Season generously with salt and pepper to taste.
Serve: Ladle the hot soup into bowls. Top with an extra dollop of vegan sour cream and a sprinkle of fresh dill or thyme if available.