Preheat oven to (400F) and lightly oil a baking sheet. Prepare the crab cakes: Whisk together the mayonnaise, sour cream, mustard and egg in a mixing bowl until combined well. Gently fold in the crab with a rubber spatula until just combined. Shape the mixture into eight 1" thick cakes and transfer to the baking sheet. Bake the crab cakes for 15 minutes or so, or until lightly golden. Run a spatula under them once or twice to make sure they're not sticking. When the cakes are ready, place them under a preheated broiler for two to three minutes or until they're lightly browned on top. Remove from broiler and let stand on the baking sheet for five minutes. Serve with lemon wedges. Notes From The Author: The key to great crab cake is the crab. You want it to be top-quality lump crabmeat and you don't want a lot of filler in the cake to interfere with the crab's subtle taste. But holding back on the filler creates a cooking problem, because crabmeat by itself (without binder) tends to fall apart in the frying pan as you're cooking it. This miraculous recipe offers the solution. There's no bread in it, but the crab cakes stay together because they're cooked on a baking sheet in the oven. These have the additional virtue of being lighter than the usual cakes, because they don't soak up butter or oil in a frying pan. And if you use wonderful, fresh crabmeat, you'll get nothing but a wonderful, fresh crabmeat flavor. Make sure that when you pick over the crabmeat you do it gently, leaving the crab in the largest pieces possible. Serve with lemon wedges, lemon mayonnaise or tarragon tartar sauce.