Place lump crab meat in a large bowl and gently pick through to remove any shell fragments. Pat crab meat lightly with paper towels to remove excess moisture if very wet. Finely dice roasted red pepper and onion; thinly slice scallions. Zest and juice the lemon.

Make crab mixture

In a medium bowl whisk together lightly beaten egg, 3 tablespoons mayonnaise, Dijon, Worcestershire, lemon juice (1 tbsp), lemon zest, Old Bay, salt and pepper. Stir in finely diced roasted red pepper, diced onion, sliced scallions, and chopped dill. Add crab meat and gently fold to combine, taking care not to break up the lumps. Sprinkle 1/2 cup fine dry breadcrumbs over the mixture and gently mix until mixture holds together when formed into a patty; add up to 1 additional tablespoon breadcrumbs if mixture is too wet.

Shape and coat

Portion mixture into 8 (2–2.5oz) small cakes for hors d'oeuvres or 4 larger cakes for main course. Lightly form into compact patties about 2–2.5 inches across. Place panko breadcrumbs on a shallow plate and press each patty into panko to coat both sides lightly; shake off excess. Transfer to a tray and chill in the refrigerator for at least 20 minutes to firm (this helps them hold shape when frying).

Pan-fry

Heat a large nonstick or stainless skillet over medium heat. Add 1 tablespoon oil and 2 tablespoons butter; swirl to heat until butter foams but not browning. Add crab cakes in a single layer without overcrowding (work in batches if needed). Cook 3–4 minutes per side, turning gently, until golden brown and heated through. Adjust heat to prevent burning; if cakes brown too quickly, reduce to medium-low and cover briefly (30–60 seconds) to heat through. Remove to a baking sheet lined with paper towels and keep warm in a 200°F (95°C) oven while you cook remaining batches.

Finish

If desired, spoon a small dollop of remoulade on each plate or serve remoulade on the side for dipping. Garnish with a small sprig of dill and a lemon wedge for squeezing.

Cajun Remoulade

In a small bowl combine 1/2 cup mayonnaise, 1 tablespoon Creole or Dijon mustard, hot sauce, prepared horseradish (if using), lemon juice, chopped roasted red pepper, chopped cornichon (if using), chopped capers, minced shallot, chopped dill, cajun seasoning, smoked paprika, salt and pepper. Whisk until smooth and taste; adjust seasoning, acidity or heat as desired (add more hot sauce for heat or a pinch of sugar if too sharp). Chill at least 15 minutes to let flavors meld.

Garnish / Finish

Arrange crab cakes on a platter or individual plates, garnish each with a dill sprig and a lemon wedge. Serve immediately with Cajun remoulade on the side.