Rinse the lentils thoroughly under cold water until the water runs clear. Set aside.
Heat the large pot over medium heat and add the olive oil. Once shimmering, toss in the diced onion and carrots. Cook, stirring occasionally, until the vegetables are soft and fragrant, about 5 minutes, and the onions are translucent.
Add the minced garlic and a teaspoon of ground cumin to the pot. Cook for about 30 seconds until the garlic is fragrant, stirring constantly to avoid burning.
Pour in the vegetable broth, and bring the mixture to a gentle boil. This will fill your kitchen with a warm, earthy aroma.
Stir in the rinsed lentils, reduce the heat to maintain a gentle simmer, and cook uncovered for 30 to 40 minutes. The lentils will become tender and start to break down slightly, thickening the soup naturally.
Occasionally stir the soup to prevent sticking. If it thickens too much before the lentils are cooked, add a splash more broth or water to keep it saucy.
Once the lentils are tender and the soup has thickened to your liking, taste and season with salt and pepper. For a creamier texture, mash some of the lentils with the back of a spoon.
Finish by squeezing fresh lemon juice into the soup and stirring in chopped herbs for brightness and freshness. Give it a final taste and adjust seasonings as needed.
Ladle the hot soup into bowls and garnish with extra herbs if desired. Serve immediately and enjoy the comforting aroma and hearty texture.