Sauté the chopped carrots, celery, and onion in olive oil in a large pot over medium heat until softened, about 5-7 minutes.

Add the minced garlic and cook for another minute until fragrant.

Stir in the lentils, vegetable broth, diced tomatoes, salt, pepper, dried thyme, and bay leaf. Bring the mixture to a boil.

Reduce heat to low, cover, and simmer for 30-40 minutes, or until lentils are tender. Remove the bay leaf before serving.

**Tip 1: Sauté vegetables for depth.** Sautéing aromatic vegetables like onions, carrots, and celery until deeply golden before adding liquids adds a rich, foundational flavor.

**Tip 2: Add a smoky element.** Incorporate a smoked paprika, a dash of liquid smoke, or even a smoked ham hock for a deeper, more robust flavor profile.

**Tip 3: Thicken with a potato or a roux.** For extra creaminess, blend in a cooked potato or whisk in a simple roux (flour and butter) at the end of cooking.