General tips
Pricking sausages used to be heresy - sous vide makes it irrelevant. The bath cooks the inside without any pressure that would burst the casing. Skip the pricking step entirely and you'll get a juicier, more flavorful sausage.
Cook at 140°F for 2 h for the modern, juicy, slightly pink texture. The 140°F mark is below traditional internal temps but completely safe due to the long hold - pasteurization happens at that temperature given enough time.
Crisp the casings in a dry pan, no oil. Sous vide sausages release their own fat as they cook, and that fat is what crisps the casing in the post-bath sear. Adding oil floods the pan and prevents the casing from getting that snappy bite.
Sear hot and fast - 60 sec per side max. The interior is already cooked and at temperature, so all you're doing is browning. Going longer overcooks the meat and dries it out. A high heat sear in a hot pan, and you're done.
Anti-tip: don't poach Italian sausages in tomato sauce after sous vide. The bath has already cooked them perfectly, and a long simmer in sauce will overcook the interior and turn the casings rubbery. Brown them, slice them, then add to sauce at the end.
Juicy & Tender tips
Don't prick sausages - keeps them juicy
Finish on grill or in skillet for color
Sweet vs hot is personal preference