Prepare the crab croquettes. Melt 2 tablespoon butter in a large saute pan over medium heat. Add the chopped onions and saute until softened, about 5 minutes. Add ¼ cup flour, stirring to combine. Add the milk and simmer for 2 minutes, stirring frequently. Stir in the crab and lemon juice and season the mixture with salt and pepper. Remove from heat and let cool completely.
Preheat oven to 425 degrees F. Drizzle 2 tablespoon on a baking sheet pan.
Set up a breading station, placing ½ cup flour in one bowl, 2 eggs in another, and 1 cup panko with 2 teaspoon togarashi in a third.
Shape the crab mixture into 6 patties, about ½ cup each. Carefully dredge the crab cakes in flour, shaking off the excess. Dip them in the egg, making sure to coat both sides then coat with the seasoned panko. Lay the crab cakes on the prepared sheet pan. Spray the crab cakes with a generous amount of cooking spray and bake in the oven for 20 minutes, flipping them over halfway through.
While the crab cakes are baking, make the cabbage slaw. Whisk together 1 tablespoon rice vinegar with 1 tablespoon oil, and 1 teaspoon sugar. Toss the cabbage with the dressing and season with salt and pepper.
Toast the bread and spread about 1 tablespoon dijon mustard on one slice. Top with a crab cake and drizzle about 2 tablespoon bulldog sauce on top. Pile on the cabbage and top with another slice of bread. Serve immediately.