Rinse and Soak the Lentils: Place the lentils in a bowl and cover them with water. Gently stir and let them soak for about 10 minutes. Drain the lentils thoroughly before using them in the stew.
Sauté the Aromatics: In a large Dutch oven or heavy-bottomed soup pot, heat the olive oil over medium-high heat until shimmering. Add the chopped onion, carrot, celery, and potato. Cook, stirring often, for 4–5 minutes until the vegetables begin to soften and develop a bit of color.
Add Garlic and Zucchini: Stir in the minced garlic and diced zucchini. Continue cooking for another 5 minutes, stirring frequently, to enhance their natural sweetness and aroma.
Add Lentils, Spices, and Tomatoes: Sprinkle in the coriander, cumin, turmeric, cinnamon, black pepper, salt, and optional cayenne pepper. Toss to coat the vegetables evenly with the spices. Add the drained lentils, followed by the diced tomatoes (with juice) and water or broth. Stir everything together to combine well.
Simmer Until Tender: Bring the stew to a gentle boil. Once bubbling, reduce the heat to low, cover the pot, and let it simmer for about 20 minutes. Stir occasionally and check for doneness—both the lentils and vegetables should be tender. Add a splash more water if needed to maintain a stew-like consistency.
Finish with Fresh Herbs and Citrus: Once cooked, remove the pot from heat. Stir in the chopped parsley and freshly squeezed lemon or lime juice to brighten the flavors. Taste and adjust seasoning if needed.
Serve and Enjoy: Ladle the stew into serving bowls and drizzle with a bit of olive oil if desired. Serve warm with slices of crusty bread for a complete and comforting meal.