In a small bowl, whisk 2 tablespoons oil, 1 garlic clove, lemon juice, and lemon zest; set dressing aside.
In a medium pot, heat 1 tablespoon oil over medium heat. Add couscous and a dash salt; sauté until most of couscous is golden brown, about 3 minutes. Add the vegetable stock, 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.
In the meantime, heat remaining 1 tablespoon oil over high heat in a large nonstick sauté pan. Add asparagus, sugar snap peas, peas, and remaining garlic clove. Sprinkle with salt and pepper; sauté until crisp-tender, about 3 minutes. Transfer vegetables to a large bowl.
Add couscous to bowl with vegetables. Drizzle dressing over. Add scallions and cheese; toss. Season with salt and pepper. Serve right away or at room temperature.
Nutritional information given is an automatic calculation and can vary based on the exact products you use and any changes you make to the recipe. If these numbers are very important to you, I would recommend calculating them yourself.