01 - Gently combine crab meat, red bell pepper, celery, green onion, mayonnaise, egg, Dijon mustard, Worcestershire sauce, lemon juice, Cajun seasoning, salt, black pepper, 1/2 cup panko breadcrumbs, and parsley in a large bowl. Mix just until combined without breaking up the crab.
02 - Shape mixture into 8 equal patties approximately 2½ inches wide. Place remaining 1/2 cup panko breadcrumbs on a plate and coat each crab cake lightly on both sides.
03 - Arrange crab cakes on a tray, cover, and refrigerate for at least 20 minutes to firm up before cooking.
04 - Whisk together mayonnaise, Dijon mustard, lemon juice, capers, cornichons, hot sauce, smoked paprika, horseradish, and parsley in a small bowl. Season with salt and pepper to taste. Refrigerate until serving.
05 - Heat butter and oil in a large nonstick skillet over medium heat. Cook crab cakes in batches for 3–4 minutes per side until golden brown and heated through.
06 - Transfer cooked crab cakes to a paper towel-lined plate to drain excess oil. Serve warm accompanied by remoulade sauce and lemon wedges.