Louisiana Deviled Crab Cakes

    1/4 cup finely chopped onion
    1/4 cup finely chopped green bell pepper
    3 tablespoons finely chopped celery
    3 tablespoons unsalted butter
    1 large egg
    1 tablespoon sour cream
    1/2 teaspoon dry mustard
    1/2 teaspoon Worcestershire sauce
    3/4 teaspoon cayenne
    3/4 teaspoon salt
    2 tablespoons thinly sliced scallion greens
    16 saltines, finely ground
    1/2 lb. jumbo lump crabmeat, picked over
    1 tablespoon vegetable oil

Cook onion, bell pepper, and celery in 1 tablespoon butter in a
10-inch nonstick skillet over moderately low heat, stirring
occasionally, until vegetables are softened, about 8 minutes.

Whisk together egg, sour cream, mustard, Worcestershire sauce,
cayenne, and salt in a large bowl, then stir in scallion, cooked
vegetables, and 1/4 cup saltine crumbs. Gently stir in crabmeat,
then form into 4 cakes (2 1/2 to 3 inches in diameter). Dredge cakes
in remaining saltine crumbs.

Heat oil and remaining 2 tablespoons butter in cleaned skillet over
moderate heat until foam subsides, then cook crab cakes, turning
once, until golden brown, 8 minutes total. Serve with tartar sauce
and lemon wedges.