In a large pot, heat olive oil over medium heat. Add the chopped onion and sauté until translucent (about 5 minutes).
Stir in minced garlic and cook for another minute until fragrant.
Add the Vegetables and Lentils:
Add the diced carrots and potatoes to the pot, along with the rinsed lentils. Stir to combine.
Pour in the vegetable broth and diced tomatoes, and bring the mixture to a boil.
Season and Simmer:
Add ground cumin, paprika, thyme, salt, and pepper. Stir well.
Reduce heat to low, cover, and let it simmer for about 30-35 minutes, or until the lentils and vegetables are tender. Stir occasionally, and add more broth or water if necessary.
Adjust Seasoning:
Taste and adjust seasoning as needed. If desired, add a squeeze of lemon juice for brightness.
Serve:
Serve the stew hot, garnished with fresh parsley if desired. Enjoy with crusty bread or over rice.