Preheat Sous Vide Machine: Add water to sous vide container or a large pot, set the Sous Vide Precision Cooker to 132°F (55.6°C).
Season the halibut filets: Season both sides with salt and pepper. Add minced garlic, thyme and butter on top of each filet.
Vaccum seal the halibut: Add sliced lemon and seasoned halibut filets into a zip-lock bag. Arrange them so that they stay in one single layer. (It’s important to cook them in one layer; if your bag is not big enough, use multiple bags.)
Vacuum seal it using “water displacement” technique: seal all but one corner of the bag. Slowly place it in the water bath, making sure everything below the zip-line is covered by water. Then seal the rest of the bag.
Sous vide cook halibut: Cook the halibut filets in the warm water bath for 30-45 minutes for 1-inch fillets, or 45-60 minutes for 1.5-inch fillets. (Make sure any part of the fish is completely submerged in the water, if you find your bag is half-floating, you can use sous vide weight magnets or kitchen metal tongs to secure it in place.)
Remove the bag from the water bath and very gently take the halibut out of the bag. (Cooked halibut tends to fall apart very easily, I recommend using a fish spatula or your hands to carefully take it out of the bag and transfer to a plate.)
Sear the fish: let your halibut cool down in the fridge for about 10 minutes. Then pat dry thoroughly with paper towels (It's important to dry it completely so that it can get browned properly in the skillet).
Place the skillet on medium-high heat and add butter. When the butter is melted, carefully add the halibut filets to the skillet presentation-side down. Sear for 30 seconds, just to brown the surface. Remove from the skillet immediately.
Sprinkle with chopped parsley and serve with lemon wedges.