Clean your seafood. Wash grit and dirt away thoroughly. For mussels throw away any that are open or cracked.
In a large pot of water add Zatarain's Shrimp and Crawfish and Crab Boil seasoning package, piece of ginger (cut into thick slices), and bouillon cubes. Bring to a boil. (If you cannot find Zatarain's seasoning packet, don't stress. Take a handful of spices - black peppercorns, bay leaves, mustard seeds, cumin seeds, old bay seasoning - whatever you have in your pantry, and tie into a cheesecloth. The point is that you want to infuse the water with lots of flavor.)
Add in your potatoes and corn. Remove when potatoes are fork-tender.
Once the water starts boiling and the flavors have been infused, add in your seafood. If using different seafoods, add each type separately. Shrimp will only take two-three minutes to cook. You will know when they are done when they curl up and turn pink. Mussels also only take a few minutes - the shells will open up when they are done.
Serve on a platter or in plastic bags combined with sauce.
In a small pot, add in butter and garlic. Allow the butter to melt and the garlic to cook.
Turn the heat on low and add in spices. Mix well and turn off the heat. (Be careful - if you leave the spices on the heat for too long, they will burn!)
Stir in the yogurt and serve right away with seafood.