Preparation Heat the olive oil in a large pot over medium heat. Add the onions and sauté until soft, about 5 minutes. Add the lentils and stir to coat them in the oil. Add the stock and bring it to a boil. Then reduce the heat to medium, cover the pot, and cook, removing any foam that rises to the surface, until the lentils are soft, about 45 minutes. Remove the pot from the heat and set it aside to cool for 15 minutes. Meanwhile, preheat the over to 400°F. Brush olive oil over both sides of the bread slices, and cut them into small cubes. Place the cubes in a single layer in a baking dish, and toast in the oven until golden and crisp, about 7 minutes. Set the croutons aside. Transfer the lentils, with their liquid, to a blender, in batches if necessary, and puree. Return the soup to the pot. (Alternatively puree the lentils right in the pot with an immersion blender.) Add the cumin, salt, and pepper and give the soup a good stir. Bring it to a boil over medium-high heat, stirring frequently. Reduce the heat to low and simmer, uncovered, for 15 minutes. Ladle the soup into bowls, and sprinkle a few croutons on top of each serving. Serve with the lemon wedges, radishes, and olives alongside. Variation:Mix 1 cup low-fat yogurt, 1/4 cup fresh lemon juice, and the grated zest of 1 lemon together in a small bowl. Spoon a bit into each bowl before serving. Reprinted with permission from The Arab Table by May S. Bsisu, © 2005