To get the desired end temperature, preheat a sous vide cooker. (Temperature and timing charts can be found here or in the note.) Salt and pepper the steaks liberally. Distribute evenly in sous vide bags with the herbs, garlic, and shallots (if using). Seal the bags, then use the charts to determine how long to keep them in the water bath.

Open your windows and turn on your vents to finish in a pan. Take the steak out of the water bath and the bag, then gently pat it dry using paper towels. A heavy cast iron or stainless steel skillet should be filled with vegetable, canola, or rice bran oil and heated over the burner with the highest heat setting until it begins to smoke.

Using a pair of tongs or your fingers, gently place the steak in the skillet. If preferred, add a tablespoon of butter; skip the butter at this point for a cleaner-tasting sear.

Flip the steak over after 15 to 30 seconds so that the other side touches the pan. Repeat this process, rotating the steak every 15 to 30 seconds, for about 1 1/2 minutes or until it has a good brown sear. If you didn't add butter earlier, do so around 30 seconds before the steak is finished cooking for more richness. Serve the meat right away.

To Finish on the Grill: Light one chimney full of charcoal. When all the charcoal is lit and covered with gray ash, pour out and arrange coals on one side of charcoal grate. Set cooking grate in place, cover grill, and allow to preheat for 5 minutes. Alternatively, set half the burners on a gas grill to the highest heat setting, cover, and preheat for 10 minutes. Clean and oil grilling grate.

Remove steak from water bath and bag and carefully pat dry with paper towels. Place steak directly over hot side of grill and cook, turning every 15 to 30 seconds, until a deep, rich crust has formed, about 1 1/2 minutes total. If the fire threatens to flare up as the steak drips fat into it, suffocate the fire by closing the grill lid until the flames die out. Alternatively, transfer steak to cooler side of grill, using a set of long tongs, until flames subside. Do not allow steak to become engulfed in flames.

Transfer cooked steak to a cutting board or serving platter and serve immediately.