Roasted Pork Sandwich with Caramelized Onions and Mushrooms

This pork sandwich recipe features roasted pork loin marinated in savory steakhouse flavors, layered onto crusty rolls with caramelized onions and mushrooms, melted provolone, and a handful of fresh baby arugula.

This pork loin sandwich recipe was originally created in partnership with Smithfield. It has been updated from the archives to include additional information, add recipe tips, and FAQs.

Creating This Roast Pork Sandwich

This pork sandwich recipe actually started as a challenge from Smithfield: come up with a new 30-minute dinner using their Steakhouse Mushroom Marinated Fresh Pork Loin Filet.

I’m always looking for fast dinner ideas, especially this time of year. School’s wrapping up, homework and after-school activities are slowing down—but summer comes with its own kind of chaos. Between family vacations, summer camps, pool afternoons, and me trying to work from home with kids around, the days still fill up fast.

It’s not impossible. But it does take some planning. Having a go-to meal that’s quick to cook and easy to customize makes a big difference.

And honestly? Sandwiches aren’t just for lunch around here. They’re one of my favorite quick dinner solutions. This roast pork sandwich checks all the boxes: thinly sliced pork, caramelized onions, sautéed mushrooms, and a slather of horseradish mayo for a little kick. You can prep all the fillings in advance, then let everyone build their own.

One kid might skip the arugula. Another adds spinach or a tomato slice. It’s simple, flexible, and gets dinner on the table without much fuss.

Keep reading for the ingredients, step-by-step instructions, and plenty of tips to make these pork sandwiches your own.

Pork Sandwich Ingredients

Here’s your ingredient checklist for these hearty pork sandwiches. Take a quick look through your fridge and pantry before you get started. Don’t forget the recipe card with exact measurements and step-by-step instructions is at the bottom of the post.

For the roasted pork:

• Olive oil – Helps sear the pork and lock in flavor before roasting.
• Smithfield Steakhouse Mushroom Marinated Fresh Pork Loin Filet – Pre-marinated and super flavorful, so you don’t have to think ahead. You can also use plain pork loin and add your own seasoning.
• Salt and pepper – Enhances the flavor of the pork and balances the marinade.
• Garlic powder – Adds a savory layer that complements the mushroom marinade.

For the Onions and Mushrooms:

• Olive oil – Used again here to sauté the vegetables until golden and tender.
• White mushrooms – Mild and earthy, they soak up the flavors of the pan.
• Red onions – Naturally sweet and perfect for caramelizing. (Learn How to Make Caramelized Onions using my tutorial)
• Salt and pepper – Just enough to bring out the depth in the veggies.

For Assembling sandwiches:

• Sandwich rolls – I like something sturdy but soft, like ciabatta rolls. Toasting them adds a little extra crunch.
• Butter – For toasting the rolls and giving them a golden, crispy edge.
• Mayonnaise – A creamy base for the horseradish sauce.
• Horseradish mustard – Adds zing and cuts through the richness of the pork and cheese. Dijon mustard works in a pinch, but I love the heat of horseradish here.
• Provolone cheese – Melts well and has a mellow flavor that pairs nicely with the pork. Feel free to swap for Swiss or mozzarella.
• Arugula – Peppery and fresh. If arugula’s not your thing, baby spinach or even lettuce works too.

What Goes with Pork Sandwiches

These pork sandwiches are rich, savory, and super satisfying—but adding a side or two can turn them into a full, well-balanced meal. Whether you’re serving them for a casual weeknight dinner or a weekend get-together, here are some of my favorite pairings:

• Traeger Grilled Asparagus – Smoky, crisp-tender, and ready in 15 minutes. If you’re already grilling something else, toss this on too.
• Garlic Sweet Potato Fries – Crispy, flavorful, and baked in the oven. These are always a hit, and they pair perfectly with anything sandwich-y.
• Creamy Jalapeño BBQ Coleslaw – Tangy, creamy, and just a little spicy. It adds great crunch to the plate (or even inside the sandwich, if you’re into that).
• Homemade Caesar Salad – A classic side that’s super satisfying. This version comes straight from Grandma Carol and goes with just about everything.
• Cucumber Tomato Onion Salad – Light and fresh with a tangy vinaigrette. It’s a great contrast to the richness of the pork.

Pork Sandwich FAQs

Have a question about this pork sandwich recipe? Here are some helpful tips, swaps, and answers to common reader questions. If you’re still unsure about something, feel free to ask in the comments—I’m always happy to help!

Can I use leftover pork loin instead of roasting it fresh?

Yes! If you already have cooked pork loin in the fridge, this is a great way to turn it into something new.

Just slice it thin, warm it gently (covered, so it stays moist), and use it in place of the roasted pork when making this recipe.

What kind of bread works best?

I like sandwich rolls that are soft enough to bite through, but sturdy enough to hold up to the fillings—think ciabatta or a good-quality French roll.

Toasting the bread helps keep everything from getting soggy.

How do you caramelize onions?

Making caramelized onions requires some patience, but it’s simpler than you thinks and so worth it! I have a post that walks you through exactly how to make caramelized onions, plus the many ways you can use them.

Don’t have the time for full caramelization? You can also just sauté them if you’re short on time.

Do I have to use arugula?

Nope. Arugula adds a little bite and some nice color, but if it’s not your thing, try baby spinach or red leaf lettuce instead.

How do I know when the pork is cooked through?

Insert it into the thickest part of the pork loin, usually right in the center. When it reaches an internal temperature of 145ºF, it’s good to go.

Let it rest for about 5 minutes before slicing to keep the juices sealed in.

What is your favorite easy dinner recipe?

Thank you for supporting the brands that support Good Life Eats. I’ve been compensated for my time in creating this pork loin sandwich recipe. As always – my opinions are my own!