Begin by adding the rinsed lentils into the crockpot, followed by the chopped onion, diced carrots, diced celery, and minced garlic.
Next, pour in the can of diced tomatoes along with their juices, followed by the vegetable broth.
Drizzle the olive oil over the mixture, then sprinkle in the dried thyme, ground cumin, and add the bay leaf.
Gently stir all the ingredients to combine, making sure the lentils are fully submerged in the liquid.
Cover the crockpot with its lid and set it to cook on low for 6-8 hours or on high for 4-5 hours, until the lentils become tender and flavorful.
About 30 minutes before serving, taste the soup and adjust the seasoning with sea salt and freshly cracked black pepper according to your preference. Remember to remove the bay leaf before serving.
Ladle the hot soup into bowls and garnish with a generous sprinkle of freshly chopped parsley for a vibrant touch.
Notes
For an appealing presentation, serve the soup in rustic bowls and accompany it with crusty whole-grain bread for a comforting meal.