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, being careful not to break up the crab too much.
02 - Shape the mixture into 8 equal patties, about 2½ inches wide. Place remaining 1/2 cup panko breadcrumbs on a plate and coat each crab cake lightly on both sides.
03 - Place crab cakes on a tray, cover, and refrigerate for at least 20 minutes to help them firm up.
04 - Mix mayonnaise, Dijon mustard, lemon juice, capers, cornichons or pickles, hot sauce, smoked paprika, horseradish, and parsley in a small bowl. Adjust seasoning to taste. Refrigerate until ready to serve.
05 - Heat butter and oil in a large nonstick skillet over medium heat. Add crab cakes in batches if necessary and fry 3–4 minutes per side until golden brown and heated through.
06 - Transfer crab cakes to a paper towel-lined plate to drain excess oil. Serve warm with remoulade sauce and lemon wedges.