In a small bowl, beat the eggs, milk, vinegar, salt and pepper until smooth; set aside. In a large skillet, cook bacon over medium heat until crisp. Remove bacon to paper towels to drain, reserving drippings.
Whisk egg mixture into drippings. Cook and stir over medium heat until mixture reaches 160° or is thick enough to coat the back of a metal spoon.
In a large salad bowl, combine the lettuce, onion and bacon. Pour dressing over salad; toss to coat. Serve immediately. Yield: 6-8 servings.