Blend first 6 ingredients in medium bowl.
Mix in crabmeat, shrimp and 1/2 cup breadcrumbs.
Season with pepper.
Place 1 cup Panko crumbs on plate. Drop 1/4 or 1/2 of crab mixture into breadcrumbs; turn to coat. Shape into 2 1/2-3 inch-diameter cake. Repeat coating and shaping with remaining crab mixture and crumbs, forming total of 2 cakes.
Chill to set cakes, approximately 1 hour
Heat oil in heavy medium skillet over medium heat. Add cakes and sauté until crisp, about 5 minutes per side.
Serve on toasted buttered brioche buns with Asian slaw and Siracha mayo. (blend of mayo with Siracha to taste)