In a medium saucepan, bring the vegetable broth to a boil. Add the couscous, stir, and remove from heat. Cover and let stand for 5 minutes, or until the couscous is cooked and the liquid is absorbed.
Fluff the couscous with a fork. Transfer it to a large bowl.
Add the diced cucumber, red onion, parsley, and mint to the bowl.
In a small bowl, whisk together the lemon juice, olive oil, salt, and pepper. Pour the dressing over the couscous salad and toss to combine.
Serve immediately or chill for later.
Notes
Feel free to add other vegetables like bell peppers or cherry tomatoes. You can also add feta cheese for extra flavor.