Preheat your sous vide water bath to 165° F (74° C).
Sprinkle the chicken thighs with salt to taste. Put them into a sous-vide-appropriate bag in a single layer (use multiple bags if necessary). Add the butter and any aromatics you choose. Seal the bag with a vacuum sealer or using the water displacement method.
When the water reaches the target temperature, put the bag in. Cook for 2 to 3 hours for bone-in chicken thighs, or 1 1/2 to 2 1/2 hours thighs.
Chill the chicken thighs (still in the bag). You can either put them in an ice bath or refrigerate them overnight.
Clean up the thighs. Remove and discard any large aromatics, such as sprigs of herbs. Pull off and set aside any gelatin or hardened butter. Pat the skin side dry with a paper towel.
Heat a pan on medium-high heat with the 2 tablespoons of oil in it. When it’s hot, put in the thighs skin-side down and sear until the skin is beautifully crispy and golden-brown, about 3 to 4 minutes. Turn the thighs over and cook skin-side up to warm through, about 1 1/2 to 2 minutes.
Finally, flip back to the skin side for 10-15 seconds to re-crisp.
Serve and enjoy!