In a medium saucepan, bring the vegetable broth to a boil. Stir in the couscous, cover, and remove from heat. Let it sit for about 5 minutes until the couscous absorbs the broth. Fluff with a fork and let it cool.
In a large mixing bowl, combine the diced cucumber, cherry tomatoes, red onion, parsley, and feta cheese.
In a small bowl, whisk together the olive oil, lemon juice, garlic powder, salt, and pepper.
Add the cooled couscous to the vegetable mixture and pour the dressing over the top. Toss gently to combine all ingredients evenly.
Chill the salad in the refrigerator for at least 30 minutes before serving to allow the flavors to meld.