Heat the olive oil in a large pot over medium heat.

Add the diced onion and sauté for 3-4 minutes until softened.

Stir in the minced garlic, diced carrots, and celery, and cook for another 5 minutes, stirring occasionally.

Add the ground cumin, smoked paprika, and dried thyme, and cook for 1 minute to toast the spices.

Add the rinsed lentils and diced potatoes to the pot, stirring to combine.

Pour in the vegetable broth and add the bay leaf.

Bring the soup to a boil, then reduce the heat to low and let it simmer for 30-35 minutes, or until the lentils and potatoes are tender.

Remove the bay leaf and season the soup with salt and pepper to taste.

Serve warm, garnished with chopped fresh parsley if desired.