Place 1 large boneless chuck roast on cutting board or sheet pan. Pat chuck roast completely dry on all sides with paper towels.

Liberally season chuck roast on all sides with seasoning salt, then place roast uncovered in refrigerator. Refrigerate seasoned roast overnight.

Fill large pot or other large, heat-resistant container with water. Note: pot must be deep enough that water level falls between minimum and maximum indicators on circulator.

Insert sous vide immersion circulator in pot of water and set to 135° Fahrenheit, or other temperature as preferred. See Notes for temperature recommendations by desired doneness.

If Chuck Roast Was NOT Dry-Brined: Place 1 large boneless chuck roast on cutting board or sheet pan. Pat roast completely dry on all sides with paper towels, then liberally season roast with seasoning salt, making sure to cover all sides of roast.

Place seasoned chuck roast in large, sealable food-safe bag. Remove as much air as possible from bag using vacuum sealer or water displacement method (see Notes below), then seal bag completely.

Once water bath is preheated to desired temperature, place bag in water, making sure chuck roast is fully submerged. If needed, use sous vide sinker weights or silverware to weigh down bag and keep chuck roast completely submerged.

Sous vide chuck roast 36 hours, or at least 24 hours, but no more than 48 hours. See Notes.

Once chuck roast has cooked for desired length of time, add 1-2 tablespoons avocado oil to large cast-iron skillet. Use more oil as needed to cover bottom of skillet completely.

Place cast-iron skillet on stovetop over medium-high heat. Heat skillet 3 to 5 minutes or until skillet is scorching hot and smoking slightly.

While skillet preheats, carefully remove bag from water bath. Unseal bag and transfer chuck roast to large plate. Pat chuck roast completely dry on all sides with paper towels.

Once skillet is preheated, place chuck roast in skillet. Sear chuck roast on each side 45 seconds or until dark brown crust develops.

When all sides of chuck roast have been seared, transfer chuck roast to cutting board. Immediately slice chuck roast, cutting against grain of meat, then serve roast with desired sides.