How to Make It
In a large pot, heat the oil over moderately low heat. Add the onion and garlic and cook, stirring occasionally, until the onion is translucent, about 5 minutes.
Add enough water to the reserved tomato juice to equal 2 cups. Add this to the onion mixture along with the tomatoes, 1 teaspoon of the salt, the cumin, black pepper, and cayenne. Crumble in the saffron. Bring to a boil, reduce the heat, and simmer, covered, for 10 minutes.
Add the monkfish. Cook until the fish is just done, 3 to 4 minutes. Stir in 2 tablespoons of the parsley.
Meanwhile, in a medium saucepan, bring 2 cups of water and the remaining 1/2 teaspoon salt to a boil. Stir in the couscous. Cover, remove from the heat, and let sit for 5 minutes.
To serve, mound the couscous onto plates and top with the fish and vegetables. Ladle the liquid over the top and sprinkle with the remaining 1 tablespoon parsley.