Heat the oil in a pot over medium heat. Add the leeks and garlic and cook until they are softened, about 4-5 minutes. Mix in flour until well combined. Slowly stir in the stock. Bring to a simmer and cook until leeks are very tender, about 20 minutes. Puree the mixture in a food processor or blender, and then return to the pot, bring back to a simmer, and season with salt and pepper. Pour soup into bowls, and then garnish the top with slices of red pepper, small pieces of cheese, and slices of fresh basil.
Note: Roasted red peppers are available in our deli.