1. Heat oven to 400°F. Scrub and dry potatoes, prick with a fork, rub with 1 tablespoon oil, and season lightly with some salt. Bake unwrapped for 50–70 minutes or until fully tender.
2. Cool about 10–15 minutes until safe to handle. Halve lengthwise and scoop out the flesh, leaving about a ¼-inch lining. Reserve flesh and refrigerate promptly if not using immediately.
3. Brush shells lightly with remaining oil. Bake cut-side down for 10 minutes, then turn up and bake 5–10 minutes more until golden and crisp.
4. Meanwhile, sauté onion and pepper in butter for 8–12 minutes until tender with browned edges. Add garlic for 30 seconds. Transfer to a plate.
5. Cook steak in batches over medium-high heat, about 2–4 minutes per batch depending on thickness, seasoning with pepper, remaining salt to taste, and optional paprika. Cook intact whole-muscle beef to at least 145°F with a 3-minute rest; follow package-specific guidance where applicable.
6. Combine cooked steak and vegetables briefly. Leave excess skillet juices behind when dividing filling among shells.
7. Top each with shredded provolone and half a slice. Bake 5–8 minutes until melted and hot. Optional: broil briefly only on suitable equipment, watching continuously.
8. Rest 2–3 minutes, garnish with parsley, and serve promptly with optional sauces on the side.

Storage: Refrigerate promptly for 3–4 days. Reheat filling to 165°F. Store shells and filling separately for best make-ahead texture.

Estimated nutrition: About 600–780 calories per dinner serving of two skins, before sauces. Ingredients, potato size, and scooping vary.

Recipe note: Cheesesteak-inspired rather than a traditional sandwich. Timing is guided by potato tenderness, crispness, and steak thickness.