Soft-shell crabs cook in minutes, are easier to eat than hard-shell crabs and their sweet, briny flavor and crunchy-soft juicy texture can't be beat. Soft-shells are usually eaten whole and they make for a killer sandwich. From Fine Cooking.
Make the Tartar Sauce: In a small bowl, combine the mayonnaise, onion, pickle, capers with spicy tartar sauce chives, Old Bay, lemon juice, and hot pepper sauce. Set aside.
To Cook the Crabs: In a wide, shallow bowl, combine the flour, cornmeal, salt and pepper. Dredge the crabs to coat on both sides.
Heat the oil in a 12-inch skillet (preferably cast iron) over medium-high heat until shimmering hot. Add the butter to the skillet and swirl the pan to melt it. Add the crabs top side down and cook, shaking the pan once or twice, until crisp and browned, about 3 minutes. The crabs may pop and splatter, so be careful.
Flip the crabs and cook until crisp and just cooked through (an instant-read thermometer inserted in the center of the crab should read 145°F), about 3 minutes more. Transfer the crabs to a large paper-towel-lined plate.
To Assemble the Sandwiches: Spread the tartar sauce on the 8 slices of toast. Top 4 of the toast slices, sauce side up, with a piece of lettuce and 1 or 2 slices of tomato. Put one crab on each sandwich, top with the remaining toast, sauce side down, and serve.