Prep all ingredients before turning on the griddle — slice meat, onions, peppers, and have cheese and rolls ready to go.
Preheat Blackstone to medium-high heat (around 400°F) for a full 10 minutes.
Add 2 tbsp vegetable oil to one section of the griddle. Add sliced onions and a pinch of salt. Cook 8-10 minutes, stirring occasionally, until soft and caramelized. Add peppers and/or mushrooms if using.
Add remaining 1 tbsp oil to a separate section of the griddle. Spread ribeye out in a thin layer — don't pile it. Season immediately with salt and pepper and add Worcestershire sauce.
Use your spatula to chop and move the meat continuously while it cooks, about 4-5 minutes, until browned with crispy bits.
Combine meat and onions into 4 equal piles on the griddle.
Place 2 slices of provolone on each pile. Cover with a basting dome if available and let melt for about 1 minute.
Butter the inside of hoagie rolls and toast butter-side down on a clean section of the griddle for about 2 minutes until golden brown.
Scoop each meat and cheese pile into a toasted roll, press down gently, and serve immediately.