This hearty soup combines protein-rich lentils with flavorful sausage for a satisfying meal. The key to developing deep flavor is to build layers by properly browning the sausage and sautéing the aromatics before adding the liquid ingredients. Don't rush the simmering process—this allows the lentils to cook properly while the flavors meld together beautifully.

1. Step 1: Break the sausage into bite-sized pieces as it cooks for even browning.

   Heat olive oil in a large Dutch oven or heavy-bottomed pot over medium heat. Add the sausage, breaking it up with a wooden spoon, and cook until browned, about 5-7 minutes.

2. Step 2: This aromatic base, known as mirepoix, builds the foundation of flavor for your soup.

   Add the diced onion, carrots, and celery to the pot. Cook until the vegetables begin to soften, about 5 minutes, stirring occasionally.

3. Step 3: Garlic burns quickly and can become bitter, so add it after the other vegetables have softened.

   Add the minced garlic and cook until fragrant, about 30 seconds, being careful not to burn it.

4. Step 4: Toasting dried herbs and spices enhances their flavor before adding liquid ingredients.

   Stir in the dried thyme, oregano, smoked paprika, salt, and pepper. Cook for 1 minute to bloom the spices and release their flavors.

5. Step 5: Always rinse lentils before cooking to remove any debris or dust.

   Add the rinsed lentils, diced tomatoes with their juices, chicken broth, and bay leaves. Stir to combine and bring to a boil.

6. Step 6: Green and brown lentils hold their shape well during cooking, making them perfect for soups.

   Reduce heat to low, cover, and simmer for 25-30 minutes, or until the lentils are tender but not mushy. Stir occasionally to prevent sticking.

7. Step 7: Bay leaves add flavor but should always be removed before serving as they can be a choking hazard.

   Remove the bay leaves. Taste and adjust seasoning with additional salt and pepper if needed.

8. Step 8: Adding greens at the end preserves their color, nutrients, and texture.

   Stir in the baby spinach and cook just until wilted, about 1-2 minutes.

9. Step 9: Acid added at the end of cooking adds brightness and balances the rich flavors of the soup.

   Stir in the fresh lemon juice just before serving to brighten the flavors.

10. Step 10: Fresh herbs added as garnish provide color contrast and a burst of fresh flavor.

    Ladle the soup into bowls and garnish with fresh chopped parsley. Serve hot with crusty bread if desired.

For a thicker soup, you can use an immersion blender to partially blend some of the soup, or mash some of the lentils against the side of the pot. For a vegetarian version, omit the sausage and use vegetable broth instead of chicken broth, adding a teaspoon of smoked paprika for depth of flavor. This soup keeps well in the refrigerator for up to 4 days and freezes beautifully for up to 3 months.