1. In small bowl, whisk together oil, lemon juice, thyme, mustard, salt, sugar and pepper. (Make ahead: Cover and refrigerate for up to 1 day; whisk before using.)
2. Tear lettuce into bite-size pieces. In large bowl, toss romaine with dressing.
3. Toss with croutons, tomatoes, cucumbers, shaved fennel, or even pears!