Tender sous vide salmon, crispy skin, with a very simple, three ingredient lemon dill sauce.
First thing is set up your water and sous vide machine. Set the temperature to 120-135°. If you want to crisp your skin up, set it to 120°. It'll give you some temperature space to get it crisped without overcooking the fish. If you're not going that route, set to 135°.
Next, we're gonna brine the fish for 30 minutes. Heat up about 1/3 cup of your 4 cups of water and mix with the salt. Once dissolved, place it in a glass pan with the remaining 4 cups of cool water and the olive oil. If the water is not cool, just toss in a few ice cubes. Place the fish in the brine and let it hang out in the fridge for about 30 minutes.
Time to whip up the lemon dill sauce. Empty the creme fraiche into a bowl or container. Zest the entire lemon and toss it in, along with the chopped dill. Add the juice from the entire lemon. Combine and chill.
After the fish has hung about in the brine for 30 minutes and you've reached your machine has gotten the water to your temperature setting, remove the fish from the brine. It's time to seal it up. At this point, if you want to add some garlic slices or lemon slices or whatever, you can. If using a vacuum sealer, seal it up. If using zip top bags, try to get as much air out as you can. Pop in the water for 20 minutes.
After 20 minutes, start getting your skillet screaming hot with some butter or oil. While that's getting hot, remove your fish. Pat dry with paper towels to ensure a good sear. When the pan is hot, place the fish in the skillet skin side down until crispy. It'll take a moment and you'll start to see white "coagulation" on the top of the fish. You're fine. Remove the fish from the pan and top with the lemon dill sauce. Enjoy!