Heat a large heavy-bottomed pot over medium heat and add a tablespoon of olive oil. When the oil shimmers and begins to smell fragrant, add the chopped onion, carrots, and celery. Sauté, stirring occasionally, until the vegetables are soft and translucent, about 8-10 minutes, and you can smell the sweetness developing.
Add the minced garlic, ground cumin, and smoked paprika to the pot. Stir constantly for about 1 minute until the spices release their aroma and the garlic is fragrant, but not browned.
Pour in the vegetable broth and add the crushed tomatoes along with rinsed lentils. Stir everything together, scraping the bottom of the pot to loosen any flavorful bits stuck there. Bring the mixture to a gentle boil over high heat.
Once boiling, reduce the heat to low and cover the pot partially with a lid. Let the soup simmer gently for about 20-25 minutes, stirring occasionally, until the lentils are tender and the soup has thickened slightly. You’ll notice a rich aroma filling the kitchen as it cooks.
Check the seasoning and add salt and pepper to taste. For an extra touch of brightness, squeeze in a tablespoon of lemon juice or vinegar, stirring well to combine.
Remove the soup from heat and let it sit for 5 minutes. This helps the flavors meld beautifully. Ladle the hot soup into bowls, garnish with fresh herbs if desired, and serve with crusty bread or your favorite side.