Trim zucchini and slice lengthwise into ¼ inch thick slices. Quarter bell pepper lengthwise discarding the seeds. Brush zucchini and pepper with olive. Grill both on lightly oiled rack 5-6 inches over glowing coals until zucchini is tender and pepper is crisp tender (about 5 minutes per side). Cut zucchini into ¼ inch and pepper into ½ inch pieces.
Mash garlic and salt to a paste.
Bring broth to a boil. Stir in couscous. Cover; remove from heat. Let stand 5 minutes. Fluff with a fork.
In large serving bowl, toss with vegetables and garlic/salt paste.