Sauté the Base Vegetables: Heat the olive oil in a large stockpot or Dutch oven over a medium heat. Add the chopped onion, carrots, and celery. Cook, stirring occasionally, for 8-10 minutes until the vegetables have softened and the onion is translucent. Don't rush this step; it's crucial for developing flavour.

Add Aromatics: Add the minced garlic, ground cumin, and smoked paprika to the pot. Stir continuously for one minute until the spices are fragrant. This toasts the spices and deepens their flavour.

Combine Ingredients: Pour in the rinsed lentils and the stock. Add the bay leaf and tomato purée, stirring well to combine everything.

Simmer Gently: Bring the soup to a boil, then immediately reduce the heat to low. Cover the pot and let it simmer gently for 30-35 minutes, or until the lentils are tender but not mushy.

Create a Creamy Texture (Optional): This is a step I always do to improve the texture. Remove the bay leaf. Using an immersion blender, carefully pulse the soup a few times directly in the pot. We're not aiming for a smooth purée, just enough to thicken the broth slightly while leaving plenty of texture from the whole lentils and vegetables. If you don't have an immersion blender, you can transfer a couple of ladles of soup to a regular blender, blend until smooth, and then stir it back into the pot.

Finish and Season: Stir in the red wine vinegar. This brightens all the flavours wonderfully. Season generously with salt and freshly ground black pepper to your taste. I find it usually needs a good amount of both.

Serve: Ladle the hot soup into bowls. Garnish with a sprinkle of fresh, chopped parsley and serve immediately with some crusty bread.