Whisk 2 tablespoons oil, lemon juice, 1 garlic clove, and lemon peel in small bowl; set dressing aside. Heat 1 tablespoon oil in heavy medium saucepan over medium heat. Add couscous, sprinkle with salt, and sauté until most of couscous is golden brown, about 5 minutes. Add 1 3/4 cups broth, increase heat, and bring to boil. Reduce heat to medium-low, cover, and simmer until liquid is absorbed and couscous is tender, about 10 minutes, adding more broth by tablespoonfuls if too dry.
Meanwhile, heat remaining 1 tablespoon oil in heavy large nonstick skillet over high heat. Add asparagus, sugar snap peas, green peas, and remaining garlic clove. Sprinkle with salt and pepper; sauté until crisp-tender, about 3 minutes. Transfer vegetables to large bowl.
Add couscous to bowl with vegetables. Drizzle dressing over. Add chives and cheese; toss. Season with salt and pepper.
Test-kitchen tip: To trim asparagus, hold onto the top of the stalk with one hand and bend the bottom of the stalk with your other hand. The stalk will snap, separating the woody end from the tender top.
Ingredient tip: Some sugar snap peas have a tough string running along the top of the pod. To remove it, snap off the leaf end and pull the string.