Combine the vegetable broth and Grano in a pot. Bring to a boil, then reduce heat to medium. Simmer, stirring frequently, until Grano is tender but still chewy, about 30-35 minutes. Use a slotted spoon to remove the tender grains from the pot, leaving the cooking liquid behind. Put the cooked Grano in a bowl and immediately dress with 2 tablespoons of the oil and a tablespoon of the lemon juice, mixing well to coat the Grano.
Return the cooking liquid to a boil, add the lentils, cover, lower the heat, and cook until the lentils are tender-20 minutes or longer.
Meanwhile, add the cucumber, scallions, yellow onion, celery, and herbs to the Grano, tossing to mix well.
While the lentils are cooking, bring the 1/2 cup of water to a boil and pour it over the couscous, tossing to mix well and soften the couscous. When the lentils are done, remove them with a slotted spoon from the cooking liquid and add to the Grano, tossing to mix well. Turn the couscous into the cooking liquid-there should be very little liquid left in the pan-and steam gently for 5 minutes or so, just until the couscous is tender. Drain the couscous well and add to the bowl with the lentil and Grano mixture. Toss all together. Adjust the seasoning, adding salt and pepper and, if you wish, the hot pepper. Set aside for 30 minutes or longer to let the grains absorb the flavoring. If necessary, add more oil and lemon juice before serving.
Adapted from recipe by Nancy Harmon Jenkins in The Mediterranean Diet Cookbook, 1994