In a medium skillet, heat 1 tablespoon oil over moderate heat. Add pepper, zucchini, onion and asparagus and saute, stirring, for 5 minutes or until crisp-tender. In a medium saucepan, bring 1- quarter cups water to a boil. Add remaining oil and couscous. Cover, remove from heat and let stand 5 minutes. Spoon couscous onto a serving platter and arrange vegetables on top.