Set your water bath to 185ºF.
Put garlic, soy sauce, chili sauce, sugar, green onions, and butter in a food processor and puree until smooth.
Pour mixture into a bag with corn and vacuum-seal. If you don't have a vacuum-sealer, you can use a freezer-safe zip bag and seal with the water displacement method. You might need to use a weight or a wedge to keep the bag submerged underwater. Sous vide for 20 minutes.
After 20 minutes, remove corn from the water bath. You can give the corn a nice char on the grill, broil on high for a couple of minutes, or use a blow torch.