In bowl, combine mayonnaise and garlic. Add crabmeat, saltine crumbs and green onions; stir just to combine. Separate into four equal portions and form into cakes.
In bowl, whisk together egg and salt. Add panko to another bowl. Dip patties first into egg mixture, then into breadcrumbs. Refrigerate for minimum 30 minutes.
Lemon Caper Dressing: In bowl, whisk together mayonnaise, milk, lemon zest, lemon juice, capers, salt and pepper.
In small nonstick skillet heat 1/2 inch (one centimeter) of canola oil to 350F. Fry cakes, flipping occasionally until golden brown. Transfer to paper-towel lined plate to drain.
Arrange lettuce, radicchio and avocado on two plates. Drizzle with dressing. Top with crab cakes. Drizzle with additional dressing. Serve with lemon (if using).