Whisk 302 grams of warm water with 8 grams of instant yeast until dissolved.
Whisk in 33 grams of granulated sugar until dissolved.
Transfer the yeast mixture to a stand mixer with a dough hook attachment.
In a separate bowl, mix 600 grams of bread flour with 14 grams of fine sea salt.
Start the stand mixer. Add the flour mixture, one heaping spoonful at a time, until fully incorporated. Let it mix for about 5 minutes until the dough is smooth.
Add 1/4 cup (56 grams) of softened unsalted butter to the dough. Mix for another 2 minutes until incorporated and smooth.
Shape the dough into a ball and place it in a greased bowl. Cover with plastic wrap.
Let the dough rise for 1 hour at room temperature, or until doubled in size.
Degas the dough by punching it down. Divide into 8 evenly sized balls and cover with a damp towel for 10 minutes.
Roll each dough ball into a rectangle about 7 by 4 inches.
Starting from the long side, roll each rectangle tightly into a log. Seal the seam and taper the ends.
Place the logs onto a baking sheet lightly dusted with cornmeal.
Cover the logs with another inverted baking sheet and wrap with plastic wrap to prevent drafts. Let proof at room temperature for 30 minutes.
Preheat the oven to 375°F (190°C).
Whisk together 1 egg white and 120 milliliters of water until thoroughly combined.
Optionally, transfer the egg wash to a spray bottle and spray the dough evenly and lightly.
Using a sharp razor, score the dough at a 35-degree angle, about a quarter of an inch deep.
Bake the logs in the preheated oven for 15 to 20 minutes.
Remove from the oven and optionally brush with melted butter. Cool on a wire rack until completely cool.
Split a hero roll, leaving one side attached, and lightly toast it on a flat top.
Increase the heat to medium-high, add a small handful of sliced sweet onions and half a thinly sliced Serrano chili. Season with salt and sauté until softened and lightly charred, about 2-3 minutes.
Add 150 grams of ground beef with the highest fat percentage possible to the flat top, spreading it out to get a good sear. Let it cook for 2-3 minutes.
Flip the beef, season immediately with salt and any other desired seasonings, then start chopping it using a spatula to get it as finely chopped as possible.
Toss the cooked beef with the sautéed vegetables, adding finely chopped raw garlic, and fold together. Layer the mixture with two slices of American cheese and mix until melted.
Add a generous drizzle of hot sauce mayo and some ketchup to the toasted hero roll.
Place the cheesy meat mixture onto the hero roll, add thinly sliced thick tomato, and finely sliced iceberg lettuce.
Immediately wrap the sandwich in sandwich paper to serve.