Bread:

1. Pre-heat the oven to 500℉ (or max temperature) and place a heavy bottom pot with a lid or a dutch oven with a lid for at least one hour.
2. In a large bowl, mix AP flour, salt, and whole wheat flour until combined; in a separate container, whisk yeast and water and allow it to sit for 5 minutes. Pour yeast mixture into the flour, and mix by hand until you form a shaggy dough.
3. Let the dough rest for 10 minutes, then knead by hand until smooth and let it rest for 15 minutes. Next, grab a small piece of the dough near the edge of the bowl, stretch as much as you can without tearing it, fold over the dough, and repeat around the perimeter until you reach the starting point. Cover with plastic wrap and let it rest for 15 minutes. Repeat this process 2 more times.
4. Cover and rise at room temperature for 1.5 hours and place in the fridge overnight. Carefully remove your dough with a bench scrapper (do not punch it down) onto a work surface, and split it in half.
5. Pre-shape your dough into a light ball by carefully scraping underneath the dough with a bench scraper while simultaneously slowly rotating. Let it rest uncovered for 15 minutes, and generously dust the top with AP flour.
6. Carefully flip the dough upside down, stretch and fold the left side over to the middle, then fold the right side over to the left. Next, fold the bottom towards the middle and stretch the top up and down to the base. Optionally stitch the sides together over one another to create more tension.
7. Gently flip it, and drag it towards you; turn it 90 degrees and drag it towards you again. Repeat this process 5 more times. Then, carefully pick up your dough with a bench scraper, and place it in a bowl with a floured clean kitchen towel or a lined floured proofing basket.
8. Repeat with the other piece of dough, cover with plastic wrap and rise at room temperature for 1 - 2 hours or until puffed and plump.  Next, carefully remove your dutch oven, and place your dough upside down. Optionally score the top of your dough with a razor or a sharp knife with an X shape. Place the lid on top and bake for 20 minutes. Remove the lid, turn the temperature oven to 450F and bake for another 15 minutes or until a deep golden brown.
9. Remove your bread and place it on a wire rack to cool down. Then, put your dutch oven back in the oven for 15 minutes and repeat with the rest of the dough.

The Steak:

1. Pre-heat oven to 225℉.
2. Optionally with the kitchen twine, tight off the beef with 3 to 4 intervals across the whole length of the roast to help cook evenly. Generously season with salt and pepper to taste.
3. Set a cast iron skillet over medium heat, and add enough oil to coat the bottom of the pan; once hot and starting to smoke, add roast, sear for 2 minutes per side until brown deep, and place in the oven for 45 minutes or until the internal temperature reads 132F.
4. Remove from the oven and rest for 15 minutes before slicing.

Assembly:

1. Set a medium size pan on medium heat, and add enough oil to coat the bottom of the pan. Once hot and nearly smoking, add onion, and green bell pepper, saute until it starts to get some color, and season to taste with salt and pepper. Cook until the vegetables soften.
2. Set a medium size pan on medium heat, and add enough oil to coat the bottom of the pan. Once hot and nearly smoking, add mushrooms, and cook for 4 - 6 minutes, stirring often or until almost cooked through,—season to taste with salt and pepper.  Reduce the heat to low and cook to your liking.
3. Set a medium saucepan over medium heat, add butter once hot and bubbling, add flour, cook stirring often for 30 seconds, then whisk in milk and continue to stir until it begins to thicken; cut the heat off and add cheddar cheese. Continue to cook until melted—season taste with salt and pepper to taste.‍
4. Sandwich Assembly - Spread mayo on both untoasted sides of your homemade bread. Add your seared mushrooms, layer on slices of beef, followed by a stack of peppers and onions, and a drizzle of mornay cheese sauce. Next, top your sandwich with the toasted side up, cut it in half, and enjoy.