- Combine oil, soy sauce, vinegar, parsley, sugar and garlic powder in small bowl.
- Cut cucumber halves crosswise into 1/8-inch thick slices and tomato into 1-inch pieces. Add to soy sauce dressing with red onion slices, stirring to combine. Let stand 1 hour; stir occasionally.
- Meanwhile, tear lettuce into bite-size pieces in large salad bowl.
- Just before serving, pour chunky dressing over lettuce; toss to combine. Serve immediately.