Combine the flour with the salt and pepper and favorite seasoning in a bowl or storage container.
Whisk or mix the egg with a fork to combine the white and yolk.
One at time, coat the crab in the egg, dredge the crabs in the seasoned flour, shake off excess flour and start frying. You want to try and time it so the crabs right from the flour into the frying pan. If you let them sit around, the flour will clump.
Heat a frying pan, large enough to hold all 4 crabs, over medium heat until hot. If you don't have a large enough pan, cook in batches.
When the pan is hot, add the butter. When the butter is hot, add the crabs to the pan bottoms up. Depending on the size of the crabs, pan fry them for 2 - 3 minutes then turn over and fry the other side for 2 - 3 minutes until golden brown.
Remove from pan, plate and squeeze a little fresh lemon juice on top. You can use the remaining lemon wedges to serve with the crabs.