Lentil and Sweet Red Pepper Soup with Cumin and Black Pepper

I use a small, plump, shrewdly marketed black lentil dubbed "beluga" for this soup, but you can use dark green French lentils or flat olive-green ones, or you can try other pulses such as split peas — green, orange, or gold. Just be prepared to adjust the amount of stock or water. Whole cumin and black peppercorns, crushed just before you add them to the soup, flavor it boldly. I have served this soup three different ways — straight from the pot, irregularly mashed in a mortar, and fully puréed in a blender or processor. Each method produces a different texture and character, and I like all three.