Sauté onions, peppers, and mushrooms (if using) until soft.
Add the steak, season with salt, pepper, and garlic powder. Cook until just browned. Set aside to cool slightly.
2. Make the Dough:
In a microwave-safe bowl, melt mozzarella and cream cheese together (about 1–2 min, stirring halfway).
Stir in almond flour and egg until combined. Knead into a dough ball.
Roll dough between two sheets of parchment paper into a rectangle (~1/4 inch thick).
3. Assemble the Roll:
Place provolone slices down the center of the dough.
Add the cooled steak and veggie mixture on top of the cheese.
Carefully fold the sides of the dough over the filling, tucking in the ends to form a log.
4. Bake:
Place the roll on a baking sheet lined with parchment.
Bake at 375°F (190°C) for 20–25 minutes, until golden brown.
5. Serve:
Let cool for 5–10 minutes before slicing.
Serve with sugar-free ketchup, garlic aioli, or just as is.