1. In a large frying pan with a lid, heat 1 tablespoon of the oil over moderately low heat. Add the garlic, couscous, cumin, cayenne, and 1/2 teaspoon of the salt to the pan. Cook, stirring occasionally, until the couscous starts to brown, about 3 minutes. Stir in the tomato juice and water. Bring to a simmer. Cover, remove from the heat, and let stand 5 minutes. Transfer the couscous to a platter or a large glass or stainless-steel bowl to cool.
2. Meanwhile, light the grill or heat the broiler. Coat the sausages with 1/2 tablespoon of the oil. Grill or broil the sausages, turning occasionally, until completely cooked through, about 10 minutes. Remove from the heat. When the sausages are cool enough to handle, cut them into thin slices.
3. Toss the cooled couscous with the lemon juice, the remaining 3 1/2 tablespoons oil and 1/4 teaspoon salt, and the tomato. Top with the sliced sausages and the cilantro.
Wine Recommendation: Australian Shiraz is an all-purpose red that marries particularly well with anything from the grill. It offers lots of ripe blackberry flavor, pepper nuances, and a soft, lush texture.