Whisk all dressing ingredients together until smooth and creamy, adding a splash of water if needed to loosen it.
Toss the lettuce, hamburger, avocado, corn, capers, pickles, red cabbage, and tomatoes in a large bowl.
Drizzle over the dressing and mix until everything is fully coated.
Finish with a big handful of French fried onions right before serving so they stay crunchy.
