Rinse the red lentils thoroughly under cold water. Dice the carrot and onion, and mince the garlic.

In a large pot, sauté the diced onion and carrot until softened. Add the minced garlic and cook for another minute until fragrant.

Stir in the rinsed lentils, vegetable broth, and diced tomatoes. Bring the mixture to a boil, then reduce heat and simmer for 20-25 minutes, or until the lentils are tender and the soup has thickened.

Season with salt and pepper to taste before serving.