Bring 1 cup fat-free, less-sodium chicken broth to a boil in a small saucepan; stir in 1 cup couscous and 1/4 cup currants. Remove from heat; cover and let stand 5 minutes. Combine 1 1/2 tablespoons extra-virgin olive oil, 1 teaspoon grated lemon rind, 1 tablespoon fresh lemon juice, 1/4 teaspoon salt, 1/4 teaspoon ground cumin, and 1/4 teaspoon freshly ground black pepper; stir well with a whisk. Drizzle dressing over couscous; fluff with a fork, and toss to combine. Stir in 2 tablespoons chopped fresh mint.