Prepare your vegetables by cutting into halves or sections. On one tray add the potatoes, onions, carrots, garlic, onions and lemons.
On a second tray add the corn, sausage and mushrooms.
Add the first tray to a boiling pot of water, seasoned with 2 cups of the crab boil seasoning and boil for 10 minutes.
Add the second tray of vegetables to the pot and continue cooking for another 10 minutes.
Lift the basket out of the boiling pot and wedge it above the water using a paddle (or whatever you use to stir your boiling pot). Allow to drain for a few minutes then add to an ice chest to keep warm.
Add all the crabs to the basket. Add the remaining crab boil (liquid and dry) to the water and bring back to a rolling boil.
Drop the crabs into the boiling water and continue a rolling boil for 8-10 mintues.
Turn off the fire and allow to soak in the water for 20 more minutes. Drain, and add crabs to the ice chest to keep warm.
For a little more than Cajun crab try adding some Cajun Fries as a side dish or maybe an appetizer.Sprinkle some seasoning over the crabs before you even start peeling. Some folks like the additional pop of flavor while sucking fingers and eating the crab meat etc. I have a great recipe for homemade cajun seasoning here.