Heat the olive oil in a large pot over medium heat. Add the onion and cook until softened, about 5 minutes.
Stir in the garlic and carrots. Cook for another 3 minutes until the garlic is fragrant.
Add the cumin, smoked paprika, and harissa paste. Stir for 1 minute to coat the vegetables and release the spices.
Pour in the lentils, diced tomatoes with their juices, and vegetable broth. Bring the mixture to a boil.
Reduce the heat to low, cover the pot, and simmer for 25 minutes until the lentils are tender.
Stir in the chickpeas and cook uncovered for 5 more minutes. Season with salt and black pepper.
Ladle the stew into bowls and top with chopped parsley. Serve with lemon wedges on the side.