1. Rinse lentils with cold water; drain. Place lentils and 4 cups water in a large saucepan; bring to a boil. Reduce heat, and simmer 20 minutes or until tender. Drain and rinse with cold water; drain.
2. Bring remaining 1 cup water to a boil in a medium saucepan; gradually stir in couscous and 1/4 teaspoon salt. Remove from heat; cover and let stand 5 minutes. Fluff with a fork. Combine lentils, couscous, remaining 1/2 teaspoon salt, tomatoes, and remaining ingredients in a large bowl.