Rinse 1 cup lentils and pick out any debris
Heat 2 tablespoons oil in a pot over medium heat
Add 1 chopped onion and cook until softened
Add 2 chopped carrots and 2 chopped celery stalks
Add 2 minced garlic cloves and cook for 1 minute
Stir in 1 teaspoon cumin, 1 teaspoon salt, and 1/2 teaspoon black pepper
Add 1 cup lentils and 6 cups vegetable or chicken broth
Add 1 bay leaf if desired
Bring to a boil
Reduce heat and simmer for 25 to 35 minutes until lentils are tender
Stir in 1 tablespoon lemon juice if desired
Remove bay leaf
Taste and adjust seasoning
Serve hot