Step 1

PREPARE CHUCK ROAST: Season chuck roast all over with kosher salt, black pepper and garlic powder. Place in fridge, uncovered, for 6-8 hours or overnight (up to 24 hours). This will enhance flavor, but if you don't have time, skip it.

Step 2

SOUS VIDE CHUCK ROAST Heat sous vide water bath to 135F/57C for medium rare (note 6 for other temps). °For water displacement method: place roast in large zipper freezer plastic bag. Lower bag into water, unsealed, until top of the bag is just above water level. Then seal bag once all air is pressed out by water. °For vacuum seal method: place roast in vacuum sealer bag. Seal bag with vacuum sealer machine. Lower bag into water. Bag should not float. Use clip to attach to side of container or hang bag over side when you put on lid. Cover container with lid, towel or aluminum foil to reduce evaporation. Sous vide chuck roast for 24 hours (or up to 30 hours). If roast is thicker than 2 inches/5 cm, you can sous vide up to 36 hours. When finished, remove beef from bag and rest it for 15 minutes. Reserve juices. Dry meat well with paper towels.

Step 3

CARAMELIZE OR CHAR ONIONS: While meat is cooking (or day before), heat skillet to medium heat and add oil, sliced onions and pinch of sugar and salt. Stir onions occasionally until lightly browned, about 10-15 minutes. Increase heat to medium-high heat for quicker results. This will char rather than caramelize onions which need a slower lower-heat cook. Set aside.

Step 4

SEAR BEEF: If you are making sandwiches, you can skip this step unless you prefer to brown the meat for presentation and extra flavor. Then grill or pan sear the meat.Spread a thin layer of mustard or mayonnaise over surface of meat. Or just spray with oil and sprinkle with salt and pepper. °To grill: Spray grill with oil and heat to high heat (500F+/260C+). Do a quick sear for 60-90 seconds per side and edges to brown it. °To pan sear: Heat large skillet to high until almost smoking. Turn on vent or open windows. Add a teaspoon or two of vegetable oil to hot pan and sear meat for 60 seconds per side and edges.

Step 5

MAKE AU JUS BEEF GRAVY: Pour the beef juices from sous vide bag into the skillet (same one you used for searing meat). I strain the juices sometimes through a fine mesh sieve to get rid of any bits but you don't have to. Add beef broth (about 1 cup/237 ml or a bit more) and thyme. Bring to boil, add cornstarch slurry and stir until thickened, 1 minute. Add seasonings as you like e.g. a dash of worcestershire sauce or sherry, a sprinkle of garlic powder, salt, pepper, red pepper flakes if you like heat. Gravy should be thin. If too thick, add more broth or a bit of water.

Step 6

MAKE FRENCH DIP SANDWICHES AU JUS; Slice bread if half. If desired, add cheese on one side (or both) and broil for about 3 minutes until cheese is melted. Slice meat across grain (the grain may be in different directions on parts of roast). Add sliced meat to au jus gravy to warm through for 1 minute max (you don't want meat to cook). Place slices on bread, top with cooked onions. Pour gravy into small individual cups. Serve sandwiches with gravy and horseradish sauce if desired.