Prepare seitan: Make TYBM’s vegan seitan beef according to the linked recipe up to the slicing step. This can be done a day or two ahead. If using store-bought seitan, take it out of the fridge to come closer to room temperature while you cook the veggies.

Sauté veggies: Heat a large skillet over medium. Add the sliced onions and green pepper. Sauté 5–8 minutes until tender and slightly charred. If the pan is dry and veggies begin to stick, splash in 1–2 tbsp water to deglaze, or use a little oil if you prefer. Add minced garlic in the last 30–60 seconds and stir. Transfer to a plate.

Warm seitan: In the same skillet, over medium-high heat, warm the thinly sliced seitan just until heated and slightly caramelized at the edges — about 2–3 minutes. Return the onions and peppers to the pan and toss to combine. Season with salt and black pepper to taste.

Make the cheese sauce: Melt 2 tbsp vegan butter in a small saucepan over low-medium heat. Once melted, sprinkle in the 2 tbsp flour. Whisk constantly for about 1 minute so the flour cooks through. Slowly drizzle in ¼ cup almond milk while whisking to avoid lumps. When the mixture is smooth and thickening, add the vegan provolone slices. Stir continuously until the cheese melts and you have a glossy, cohesive sauce. If the sauce is too thick, whisk in more dairy-free milk 1 tbsp at a time until desired consistency.

Optional blending: For an ultra-silky cheese sauce, transfer it to a mini blender or processor and blend on high for 30–60 seconds. Return to the pot and reheat gently if needed.

Toast the hoagies: Brush the insides of the rolls with 1–2 tbsp melted vegan butter. Toast in a hot skillet or under the broiler for 1–2 minutes until golden.

Assemble: Pile seitan, peppers, and onions into each hoagie. Spoon the provolone sauce over the filling, or tuck slices of vegan provolone into the warm meat mixture so they melt slightly. Serve hot.