Place couscous in a medium heatproof bowl. Pour 1 cup boiling water over the couscous, cover, and let stand 10 minutes. Fluff with a fork.
Cut bell pepper into 1-inch-long matchsticks, and add to the warm couscous. Thinly slice the scallions crosswise, and add to the bowl. Add cherry tomatoes.
In a small bowl, whisk olive oil and lemon juice together. Season with salt and pepper. Drizzle over couscous, vegetables, and toss. Garnish with lemon zest, if desired, and serve.
Super good, super simple. I had no idea how lovely the bell pepper would taste with the couscous, but it's a great combo. For some extra flavor, I suggest using chicken broth instead of water with the couscous. I recently tried it and it just added that extra bit of savory.