Step 1: Sauté Vegetables

1. In a large pot or Dutch oven, heat the olive oil over medium heat.
2. Add the diced onion, carrots, and celery. Sauté for about 5–7 minutes until the vegetables are softened.
3. Stir in the minced garlic, oregano, thyme, and red pepper flakes (if using). Cook for another 1–2 minutes until fragrant.

Step 2: Add Lentils and Broth

1. Add the rinsed lentils, diced tomatoes (with their juices), and vegetable broth to the pot. Stir to combine.
2. Increase the heat to bring the mixture to a boil, then reduce the heat to low and cover the pot.

Step 3: Simmer the Soup

1. Let the soup simmer for about 30–35 minutes, or until the lentils are tender. Stir occasionally and add more broth or water if the soup becomes too thick.

Step 4: Add Greens and Season

1. Once the lentils are tender, stir in the chopped spinach (or kale) and cook for an additional 5 minutes until wilted.
2. Taste and adjust seasoning with salt and pepper. If desired, add lemon juice for brightness.

Step 5: Serve

1. Ladle the soup into bowls and garnish with fresh parsley. Serve hot with crusty bread or a side salad for a complete meal.