Fill a 10-gallon stockpot half full with water. Add the seasoning and bring to a rolling boil. Add the whole potatoes to the pot. Allow the water to return to a boil and cook for 5 minutes. Add the onions and sausage. Bring the water back to a boil and cook for 15 minutes. Add the corn, bring the water back to a boil, and cook for 10 minutes, or until the potatoes are done. Add the shrimp, bring the water back to a boil, and cook until the shrimp turn pink, about 3 minutes. Drain through a colander, discard the liquid, and serve on a large platter or on newspaper.