Fried Soft Shell Crabs is a great Cajun Cooking Recipe and most often considered a delicacy in Louisiana Cooking. 

Clean the crabs as shown Here and rinse them off. Begin by preparing your mixes.

Wet mix
2 eggs
1 cup of milk
1/2 cup Italian Dressing
1 tbs. Creole Seasoning (your choice)
1/2 tsp. garlic powder
1/2 tsp onion powder
1 tsp. hot sauce
1 tsp. cayenne pepper
Salt and fresh ground black pepper.

Put crabs in liquid mix. Mix it all up and marinade it for 30 or more minutes in the ice box. 

Dry Mix
2 cups plain flour.
3/4 cup cornstarch (makes it stick better)
2 Tbs. Creole Seasoning
1/2 tsp Salt
1/2 tsp. Black Pepper
1/2 tsp. Cayenne
1 tsp lemon and pepper seasoning

Cooking:

Dredge the crabs in the dry mix and let sit a minute or so moving them around just a little. 

Use peanut oil, about 1 1/2" in the pan depending upon the pan depth. Heat to 375ºF (hot oil will burn you badly, be careful). Place the crabs in the oil leaving a 1" space between them, in other words don't try to fry too many at a time. Overloading the pan will cool the cooking oil too much and you'll get soggy crabs.  Stir them around every 10 seconds or so.

Timing: Cook them about 3 minutes flipping a few times. I watch the bubbling to judge the doneness, I don't time them. Let them fry until they bubble lightly. If they quit bubbling completely they're overcooked. With practice you can get each piece done perfectly. You cannot tell how done the crabs are by the outer color, it's all in the bubbles! Remove the crabs and place on paper towels. Move them around so the grease is soaked up.  Transfer them to another pan with more paper towels and cover with paper towels. 

Let the oil come back to 365ºF for the next batch! 

Note: Remember, the oil cools as you cook.  If you don't have a frying thermometer get one, guessing just won't get it! If the oil gets too hot turn the fire off and let it cool to the right temperature. If the oil smokes you've probably ruined it. A thermometer prevents all of this trouble.

Enjoy!