In a large pot, bring the couscous and broth to a boil over medium heat. Lower the heat to bring to a simmer. Cover and let simmer for 10 minutes, until the couscous is tender and the liquid has been absorbed.
Drizzle in the olive oil and stir to coat. Add the garlic and zest and stir to combine. Add the lemon juice, tomatoes, olives, mint, and cheese. Stir to combine. Season with salt and pepper to taste.