To prepare dressing, combine first 7 ingredients, stirring with a whisk.
To prepare lentils, combine water and next 5 ingredients (water through rosemary) in a medium saucepan; bring to a boil. Cover, reduce heat, and simmer 18 minutes or until lentils are tender. Drain; discard thyme and rosemary. Place lentil mixture in a large bowl; stir in tomato, olives, parsley, and onions. Pour dressing over lentil mixture; toss to coat.