Working in batches, cook the pancetta in a large nonstick skillet over medium heat, turning occasionally, until crisp, about 6 minutes. Drain on paper towels; set aside.
Meanwhile, make the dressing: Combine the mayonnaise, sour cream, parsley, tarragon, chives, anchovy, garlic, lemon juice and 1/4 teaspoon salt in a blender; puree until smooth.
Combine the lettuce, arugula, hearts of palm, crabmeat and avocado in a large bowl. Add the dressing, 1/4 teaspoon salt and a few grinds of pepper and toss. Serve topped with the pancetta.
Photograph by Johnny Miller
Recipe Courtesy of Food Network Magazine