Pre-freeze steak on a sheet pan, then vacuum seal it.
Place vacuum sealed steak into 131 degrees F water for 1 hour (can leave it for up to 4 hours).
Remove steak from vacuum sealed bag, pat dry, and season with salt and pepper. Allow it rest a few minutes while you pre-heat a cast iron skillet.
Add 1/2 tbsp of avocado oil to a cast iron skillet and heat over medium high heat just until skillet begins to smoke.
Lay steak into skillet and add 1/2 tbsp butter. Quickly sear steak on each side (and edges), flipping every 15-30 seconds until browned, but no more than 2 minutes total.
Slice and serve the steak immediately (there's no need to rest a sous vide steak).