Heat olive oil in a large pot over medium heat and add the chopped onion, carrots, and celery, cooking for 7-8 minutes until vegetables are softened.
Add the minced garlic, cumin, and thyme, stirring constantly for 1 minute until aromatic.
Stir in the rinsed red lentils, vegetable broth, and bay leaf, then bring the mixture to a boil.
Reduce heat to medium-low and simmer uncovered for 25-30 minutes, stirring occasionally, until lentils are tender and soup has thickened.
Remove the bay leaf and season with salt and pepper to taste.
Serve warm, optionally garnished with fresh parsley or a squeeze of lemon juice.