Roast beef and gravy: preheat your oven to 275 F (135 C).

Liberally salt the exterior of the chuck roast and allow it to sit on a cutting board for 30 minutes. After the beef has rested, dry off the exterior with paper towels to ensure it is dry. The salt will bring moisture to the surface and if the surface of the meat is damp it will not sear properly in the next step. So, dry it off.

On your stove, over high heat place a large pot or Dutch oven. Add 3 tablespoons of oil and allow it to heat up until the oil is shimmering. Once the oil is shimmering, add the roast and sear it on each side for 7 minutes. Once at least 3 sides have been seared remove the roast to a plate to rest for the next step.

Remove the pot from the heat and allow it to cool for 5 minutes while you chop your onions and mushrooms. After 5 minutes, add the pot back to medium heat and add 3 tablespoons of butter.

Once the butter is melted and bubbly add onions and mushrooms and cook for 4 or 5 minutes to soften them.

Add the minced garlic and cook for around 1 minute, stirring everything together.

After 1 minute, add 3 tablespoons of all-purpose flour, stir, and cook for another 1 minute to cook off the flour taste.

Pour 1/2 cup wine, 1 tablespoon of Worcestershire sauce, and 1 tablespoon of beef bouillon base into the onions and mushroom mixture. Stir everything well to combine and as soon as it's all combined you can add 3 cups of beef stock and 2 bay leaves.

Bring everything to a simmer and then add the chuck roast back into the pot. Taste the gravy for seasoning. If it doesn't seem salty enough, add 1 or 2 teaspoons of salt.

Place the lid on to cover the beef and gravy and place in the oven to bake for 4 hours. 

After 4 hours remove the pot from the oven and remove the lid from the pot. Allow the beef to rest in the gravy for 30 minutes. Once 30 minutes have passed, remove the beef to a sealed container or wrap it in plastic and foil and place it in the refrigerator to cool. It's easier to slice when it is cool.

Remove the bay leaves from the gravy and place the gravy in another sealed container to be used later when it's time for sandwiching.

After about 2 hours you can slice the meat into 1/4 inch or thinner slices. Or you can wait until it's time for sandwiches to slice.

French fries: using a mandoline or a sharp knife, cut your potatoes into 1/4 inch planks and then into 1/4 inch spears of potato.

Add all your potatoes to a large bowl of water for at least one hour. This allows the excess starch to be removed from the potatoes.

After an hour or so, drain the potatoes and dry them with paper towels. Attempt to get them as dry as possible. 

Add your oil to a large heavy-bottomed pot. You need your oil to be at least 3 inches deep in the pot.

Bring the oil temperature up to 300 degrees F and fry all your potatoes in batches for 3 to 5 minutes. This first stage is to cook the potato all the way through. This isn't going to make your fries turn brown and crispy. That comes in the second fry.

After 3 to 5 minutes, move the par-cooked potatoes to a rack to cool and cook the rest of your potatoes in batches. 

Once all your potatoes have been fried once, raise the temperature of your oil to 375 F. 

Once again fry your potatoes in batches until they turn golden brown for 1 to 2 minutes. 

Move each batch of fries to a bowl or plate and salt immediately while they are still warm. 

Sandwich assembly: in a small pot add beef and a couple of large spoonfuls of gravy. Cook over medium heat for about 5 minutes or until the meat and gravy are warmed all the way through.

Spread mayonnaise on both interior sides of your sub roll.

Top the bottom of the roll with beef and spoon on any extra gravy. Top the beef and gravy with a handful of crispy fries.

Add lettuce, tomato slices, and pickles on top of the fries, and top the whole sandwich with the top of the sub roll.