In a large bowl, pour boiling water over the couscous. Cover and let it sit for 5 minutes until the liquid is absorbed.
Fluff the couscous with a fork and let it cool to room temperature.
Once cool, add cherry tomatoes, cucumber, red onion, and parsley to the couscous.
In a small bowl, whisk together olive oil, lemon juice, salt, and pepper.
Pour the dressing over the couscous salad and toss until well combined.
Serve immediately or refrigerate for up to 2 hours before serving to allow flavors to meld.