Philly Cheesesteak Sandwiches with Smoked Rib Roast (The Best Way to Use Leftover Prime Rib)

This is the sandwich I make the day after a smoked rib roast, when there’s beef left in the fridge and I want lunch to feel like a reward. A proper Philly cheesesteak recipe usually starts with raw ribeye, but leftover smoked rib roast gives you something better: deep, smoky flavor that’s already there before you even hit the skillet.

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This is the perfect use of my Smoked Rib Roast, and with a few tips, you’ll get perfect beef for slicing. Smoked beef is already cooked, so it goes in the pan last and barely warms through. Everything else (the onions, the mushrooms, the peppers) gets the heat and the bulk of the cooking time. Two hoagies, ten minutes of actual work, and you’ve turned leftovers into something I’d happily order out.

Chef Jenn’s Take on Philly Cheesesteak Sandwiches

The biggest mistake people make with leftover prime rib sandwiches is treating the meat like raw steak. They throw it in the pan, walk away for five minutes, and come back to gray, chewy beef that’s lost everything that made it worth saving in the first place.

Instead, add the beef at the last minute, cook your vegetables hard and fast until the onions have real color and the mushrooms are properly browned, then add the beef at the very end for 60 to 90 seconds, just to take the chill off. The smoke flavor is already in the meat. Your job is to keep it there.

What You’ll Love About These Philly Cheesesteaks

• The smoked rib roast does most of the flavor work for you. There’s no sad beige sandwich meat here, the smoke is already baked in and you taste it in every bite.
• Ten real minutes of cooking once the vegetables hit the pan, which means this is a leftovers lunch, not a leftovers project.
• Mushrooms in a Philly are controversial, but I love them. They give the sandwich body, soak up the butter, and stretch a small amount of beef into two full hoagies.

Ingredients

• Smoked rib roast – Slice it cold from the fridge, not at room temp. The colder the meat, the thinner you can cut it. Any leftover smoked or roasted beef works: prime rib, ribeye roast, even tri-tip.
• Hoagie rolls – Soft on the inside, slightly sturdy on the outside. Skip anything too crusty or it’ll fight you with every bite. A good bakery sub roll is what you want.
• Provolone cheese – Real provolone, not the white American sometimes sold as “provolone.” If you want the Philly purist version, swap in cheese sauce. White Americans work, too, if that’s your preference.
• Green bell pepper – Optional. Some Philly cheesesteaks have peppers, some don’t. I include them. Red bell pepper works if green is too sharp for you.
• Onion – Yellow or sweet. Cook them harder than you think you need to. Pale, half-cooked onions ruin a cheesesteak.
• Mushrooms – Cremini or white button. Slice them on the thicker side so they don’t disappear into the meat.
• Butter – Salted is fine. The fat is for cooking the vegetables and finishing the bread.
• Salt and black pepper – Season the vegetables, not the beef. The smoked roast is already seasoned from when you cooked it the first time.

How To Make Philly Cheesesteak Sandwiches with Smoked Rib Roast

Scroll down for the full recipe card with exact measurements and printable instructions.

Slice the bell pepper, onion, and mushrooms thin. Then slice the smoked rib roast as thin as you can manage, working against the grain. Cold meat from the fridge slices cleaner than room-temperature meat, every time.

Heat a large skillet or flat griddle over medium-high heat and melt the butter. You want the pan hot enough that the onions sizzle the moment they hit it. Add the onion first and cook for 2 to 3 minutes, until they soften and start to take on color around the edges.

Add the mushrooms next and let them go for 5 to 7 minutes. They’ll release water first, look gray and sad, and then start to brown. Don’t add the peppers until that browning happens, or you’ll end up with steamed mushrooms instead of sautéed ones.

Add the bell pepper and cook another 2 to 3 minutes until tender and lightly caramelized at the edges. Season the vegetables with salt and black pepper, then push them all to one side of the pan.

Add the sliced smoked rib roast to the empty side of the pan and warm it gently for 60 to 90 seconds. This is where most cheesesteak recipes go wrong. The beef is already cooked. You are reheating, not cooking. Chop the meat lightly with the edge of a spatula and combine it with the vegetables.

Divide the mixture into two portions on the griddle and top each with two slices of provolone. Let the cheese melt for about a minute. While that happens, toast the hoagie rolls cut-side down on a clean spot in the pan, or under the broiler for 60 seconds, just until the inside is barely crisp.

Slide a spatula under each cheese-topped pile and flip it straight into the toasted roll. Press gently to settle everything in. Serve immediately.

Make It A Meal

I serve these with something sharp to cut the richness; the cheese and butter and beef are doing a lot of work and the side should push back. A scoop of my favorite Warm German Potato Salad is my go-to, the bacon and vinegar are exactly the contrast you want. If you’d rather lean into the leftover-roast theme, my Leftover Roast Beef Stew works for the next day’s dinner from the same roast. For dunking, I always put out a small bowl of Spicy Garlic Aioli for the fries that go with these. And if you want another smoked-meat sandwich for the rotation, my Pastrami Reuben Sandwich is the next stop.

Storage

Store leftover filling (without the bread) in an airtight container in the fridge for up to 3 days. Reheat in a skillet over medium heat with a small splash of water or broth to bring back the moisture. I don’t recommend freezing; the cooked vegetables go watery on thaw. Toast fresh hoagie rolls when you’re ready to rebuild the sandwich.

Frequently Asked Questions