Heat the olive oil in a large pot over medium heat. Add the onion and cook until it softens, about 5 minutes.
Stir in the garlic and cook for 1 minute until fragrant.
Add the lentils, cinnamon, cumin, smoked paprika, and turmeric. Stir for 1 minute to coat the lentils with the spices.
Pour in the vegetable broth and the diced tomatoes with their juice. 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 for 5 more minutes until heated through. Season with salt and pepper.
Serve the soup with lemon wedges on the side.