Sous Vide French Dip Sandwiches

This roast cooks sous vide for 18 to 24 hours, so it's important to begin cooking with your serving time in mind. Calculate backward from your dinner time to figure out when you should start cooking the roast.

For make-ahead instructions if you don't plan on serving your sandwiches right away, see the instructions in the headnotes.

Trim any large pieces of fat from the exterior of the roast, but don't worry about getting every last speck. Season it on all sides with the salt and pepper.

Warm a large skillet over medium-high heat and add 1 tablespoon of oil. When the oil shimmers and glides smoothly, and a flick of water evaporates on contact with the pan, add the roast.

Sear the roast very well on all sides, 4 to 5 minutes per side. The seared surfaces should look dark reddish-brown. If the oil starts to get smoky, lower the heat slightly; otherwise, maintain a medium-high heat for the best sear.

If the roast is still scorching hot from the pan when you put it in the plastic bag, it can melt a hole in the plastic.

With the pan still over medium-high heat, add the wine all at once. It will bubble and steam as it hits the pan. As it bubbles, use a stiff spatula to scrape up any dark bits that were stuck.

Once you've scraped up all the bits and the wine is simmering, pour it carefully into a measuring cup. Let it cool slightly.

Place a 1-gallon plastic freezer bag on your counter and fold the top outwards to form a cuff; this will help it stand up and make it easier to fill. (Alternatively, place the bag in a bowl while filling).

Place the slightly cooled roast into the bag. Pour the wine and broth over top, and tuck the bay leaf inside. Zip the bag almost entirely shut, leaving about an inch open at one edge.

Seal the bag: Fill a large stock pot three-quarters full with water. Submerge the bag with the roast until just the zipper part of the bag is above the water.

As you submerge the bag, the pressure of the water will press the sides of the plastic bag up against the roast and the liquid, "hugging" the ingredients. You may need to use your hands or a spatula to poke the roast below the surface of the water and force out any bubbles.

Once all the air bubble are out, submerge the bag up to the zipper, then zip it all the way closed so the bag is sealed. Lift the roast from the water and place it on a dishtowel while you heat the water.

As you lift the bag, the plastic should look like it's hugging the ingredients inside the bag. A few small air pockets are fine; vacuum-sealing isn't necessary. Check carefully to make sure the bag isn't leaking; if it is, transfer it to a new bag and repeat this sealing step.

• Read more about this method here.

Place the pot of water on a trivet or other heatproof surface. Place the immersion circulator in the water and set it to heat the water based on your preferred doneness for the roast beef: 135°F (medium-rare), 140°F (medium), 145°F (medium-well) or 150°F (well-done).

It will take approximately 5 to 10 minutes for the water to heat, depending on the volume of water in your pot. (You can also use warm water out of the tap to cut down on heating time.) Once the water is up to temp, your immersion circulator will indicate that you're ready to start cooking.

With Joule, this is controlled through the Joule app: Open the app on your phone and press the orange circular button in the bottom right corner. Input the temperature and press the orange button again to start the device and begin heating the water.

Once the water has finished heating, lower the roast into the water. It's fine if the zipper is above the surface of the water, but the roast itself should be completely submerged by at least an inch or so. Add more water if needed.

Cook the roast for 18 to 24 hours (yes, hours!). It will become more tender the longer you let it cook. Set a timer so you know when it's ready.

Every so often during cooking, take a peek at your roast and make sure that it's still submerged in the water and the bag isn't leaking. (If it's leaking, the liquid will start to look diluted and you'll notice air bubbles in the bag. Just transfer the roast and liquid to another bag and carry on with cooking. This doesn't happen very often, but is something to watch out for.)

Keep an eye on the water level and add additional water if it looks like it's getting low. The immersion circulator will heat the water right back up to temperature. To help prevent evaporation, you can also cover your pot with plastic wrap, a silicon bowl cover (as I have), or any other cover.

At any point during this cooking time when you have a spare 10 minutes, cook the onions. Warm a teaspoon or two of oil in a skillet and cook the onions with 1/4 teaspoon salt until they are very soft and browned.

If you're not serving them right away, cool and refrigerate until needed. To reheat, add them to a hot skillet and stir until warmed through.

When you're done cooking the roast, lift the bag from the water and set it on a kitchen towel on the counter. Warm a tablespoon of oil in a large skillet over medium-high heat.

Open the bag with the roast; be careful not to spill any of the cooking liquid. Use tongs to lift the roast from the bag and transfer it to a cutting board. Pat it dry on all sides.

Transfer the roast to the hot skillet and sear on all sides, 2 to 3 minutes per side, until the outside is very crusty. Add more oil as needed to the pan. Once seared, set the roast on a cutting board until ready to slice.

While the roast sears, strain the cooking liquid ("jus") into a measuring cup. Taste and add salt or pepper if needed. If the jus seems overly concentrated to you, add a little water to thin it out again.

Use a little of the jus to deglaze the pan after searing the roast, if you like.

Transfer the jus to individual cups for serving.

Warm the oven to 400F. Open up all the French rolls and arrange them in a single layer on a baking sheet with the cut sides facing up. Toast in the hot oven until they are warm and feel crispy when you press the surface of the bread, about 5 minutes. Remove from the oven, but leave the oven on.

If you like, spoon a little of the beef jus over the bottom buns for flavor.

Use a sharp chef's knife and slice the beef against the grain as thinly as possible.

Pile slices of beef on the bottom half of the rolls. The meat should divide equally between all the rolls, but you may have some leftover.

Top each pile of beef with some onions and a slice or two of cheese, if desired.

Set aside the tops of the buns so they don't burn. Switch the oven to "broil" and slide the pan of sandwiches under the broiler. Broil until the cheese starts to melt, about 1 minute.

Top each sandwich with the top bun. Serve with the jus alongside for dipping. (Refrigerate leftovers and consume within 3 to 4 days, or freeze for up to 3 months.)