Preparation

• Tear up the bread and pulse it in a food processor to make fine, soft crumbs (you should have about 3-1/2 cups). Pour the crumbs into a 9×13-inch (or similar-size) dish and mix in 3 Tbs. of the parsley.
• In a food processor, combine the egg yolk, vinegar, mustard, bell pepper, onion, Tabasco, paprika, thyme, 1/2 tsp. kosher salt, 1/4 tsp. pepper, and the remaining 2 tsp. parsley. Pulse to finely mince the vegetables and combine all the ingredients. With the motor running, slowly add the oil through the feed tube until the mixture emulsifies and forms a thin mayonnaise.
• Transfer the mayonnaise to a large bowl and stir in the sour cream. Use a rubber spatula to gently fold in the crabmeat, taking care not to break up the lumps. Pour the crab mixture onto a large rimmed baking sheet and portion it into eight equal mounds. Gently shape each mound into a patty about 3 inches wide and 1/2 inch thick. (The mixture will be quite wet.)
• Using a spatula to move the patties, lightly dredge each patty on both sides in the reserved breadcrumb mixture. Cover the crab cakes with plastic wrap and chill for at least 1 hour. (You can leave the cakes right in the pan of breadcrumbs and chill them as long as overnight.)
• Heat the oven to 200°F. Heat 3 Tbs. of the butter in a large nonstick skillet over medium heat. When the butter melts, add four crab cakes to the pan. Gently fry the crab cakes until they’re golden brown on both sides and heated through, turning just once with a spatula, about 4 min. per side. Transfer the cakes to a plate (don’t cover) and keep them warm in the oven. Wipe the skillet clean and cook the remaining crab cakes as above, using the remaining 3 Tbs. butter.
• Serve hot, accompanied by ramekins of cocktail sauce and lemon wedges.

Make Ahead Tips

You can shape the crab cakes up to 24 hours before you cook them.