Before I purchased the immersion circulator, MANY of the articles I read on cooking sous vide described it as being much easier and simpler than cooking in a traditional way (oven, grill, pan etc...). All of my experiences cooking sous vide says the opposite. The immersion circulator lets you control texture and doneness; it does little, in my opinion, for flavor and you no longer have the crust that comes from searing. It is, however, amazing how juicy the meat is. After tinkering with the method for some time, this creates my favorite pulled pork but it does take some work.
MY METHOD
Dry Rub: Apply any drub you prefer.
Alton Brown's recipe is a good base and allows for customization depending on personal taste (I added curry powder, garlic powder, onion powder, cumin, cayenne and some liquid smoke). A little extra brown sugar gave the nice bark from the image above. I added some more salt and brown sugar than normal. I vacuum sealed the pork shoulder and left it in the fridge for two days. the extra salt and vacuum sealing (cut the bag a little long, then reused the bag for the immersion circulator portion) added a cured ham flavor to the meat. In previous trials, less salt and sugar meant the shoulder came out with a flavor and texture closer to brisket. Both are pretty good. If you really like that cured ham flavor, some pink salt (nitrite salt) might be something to try.
UPDATE: DON'T DO THE SEAR. Having a constantly wet surface on the meat instead of searing will allow the smoke flavor to penetrate MUCH better. Skip drying the surface and the sear and just start smoking on the cooler side of the grill.
Grilling: Prep the meat buy removing it from the bag, patting it relatively dry (leave as much of the dry rub as possible since it makes a great crust) and letting it sit in the fridge on a drying rack for at least thirty minutes; this really dries out the surface of the meat. Having a dry surface on the meat will give a better sear and keeping it cold keeps the heat from searing from penetrating too deep into the meat. I like to use lump charcoal for searing since it burns hotter and briquettes for the smoking portion since it burns longer (I hate having to light and add more coal). After lighting some lump charcoal in a chimney starter, adding it to one side of the grill and letting the grill grates (cast iron grates are my favorite) get nice and hot I seared the meat. I like to get a fair amount of burnt sections on the surface. I wouldn't be too worried about black char on the surface since cooking sous vide will mellow out any burnt flavor. After you get a good sear/char, move the meat to the cool side of the grill.
Smoking: There are many woods to choose from, I prefer hickory, and many ways to get the smoke going. I like to take an old cast iron skillet, fill it with hickory chips and cover it with aluminum foil with a few small holes poked in it. You don't want the wood to burn since it will give the meat a sooty flavor. The aluminum foil keeps it from getting too much oxygen and burning. Suspend the cast iron skillet of wood chips above the coals so the chips begin smoking but do not catch fire. Make sure to put a pan of water underneath the meat (on the side without coals) to keep the exterior of the meat moist. If the surface gets dry, the smoke flavor will not penetrate the meat as well.
Cooking in a Water Bath: Set your circulator to 60 degrees celsius, bring the water to temperature, vacuum seal the meat and drop it in for twenty four hours. Slice across the grain and enjoy.
The meat is very soft, incredibly juicy and the sugary/salty crust is my favorite part of the dish.