Heat the olive oil in a large pot or Dutch oven over medium heat. Add the finely chopped yellow onion, diced carrots, and diced celery. Sauté the vegetables for about 8-10 minutes, stirring occasionally, until they have softened and the onion is translucent. This process builds the aromatic base of the soup.

Add the minced garlic to the pot and cook for another minute until fragrant. Be careful not to burn the garlic, as this can make it bitter.

Stir in the rinsed and picked-over lentils, vegetable broth, and undrained diced tomatoes. Add the dried thyme, bay leaf, and smoked paprika. Stir everything together to combine.

Bring the soup to a boil, then reduce the heat to low, cover the pot, and let it simmer gently for 30-40 minutes, or until the lentils are tender. Stir occasionally to prevent sticking to the bottom of the pot.

Once the lentils are tender, remove and discard the bay leaf. Season the soup generously with salt and freshly ground black pepper to taste. Start with a small amount of salt and add more as needed.

For a smoother consistency, you can use an immersion blender to partially blend the soup, or transfer about 2 cups (475ml) of the soup to a regular blender, blend until smooth, and return it to the pot. Blend only a portion to retain some texture.

Ladle the hot lentil soup into bowls. Garnish each serving with freshly chopped parsley and serve with lemon wedges on the side. Squeezing fresh lemon juice over the soup just before eating brightens the flavors.