Cook the green onions and bell pepper in 1 tablespoon of the oil in a 12-inch nonstick skillet over medium heat for 2 minutes or until slightly softened, stirring twice. Spoon the mixture into a medium bowl; wipe out the skillet.
Meanwhile, process the bread slices in a food processor until fine crumbs form (about 1 cup crumbs). Place the breadcrumbs, egg, 2 tablespoons of the Parmesan cheese and black pepper into the bowl with the onions and bell pepper; mix well.
Fold in the crab meat. Press the mixture together and shape small 2-inch patties using about 2 tablespoons of the mixture for each. Mix the Panko breadcrumbs and remaining 2 tablespoons Parmesan cheese in shallow bowl or pie plate.
Drop the patties into the breadcrumb mixture and turn and pat to coat completely. Place the patties on a clean plate. Heat the remaining tablespoon of oil and the butter in the same skillet over medium-low heat.
Add the crab cakes. Cook about 3 minutes or until deep golden brown; turn carefully and cook 2 to 3 minutes or until deep golden brown and thoroughly heated in center. Mix the sour cream, basil, lemon juice and lemon peel in small bowl and serve as a topping for crab cakes.