Sauté onion in olive oil in a 2- to 3-quart heavy saucepan over moderate heat, stirring occasionally, until golden, about 3 minutes. Add garlic and cook, stirring, 30 seconds. Add water and broth and bring to a boil.
Stir in couscous, then cover and remove from heat.
Let couscous stand, covered, 5 minutes, then fluff with a fork and stir in herbs, lemon juice, mint oil, and season with salt and pepper.
Variations: Couscous is a nice alternative to rice and a perfect base for salads.
Other ideas for add-ins: O&CO. Semi-Dried Tomatoes, toasted pine nuts, feta cheese, roasted peppers, O&CO. Tomato powder, O&CO. Pesto or chopped cooked chicken.