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Roast beef panini recipe with caramelized onions and horseradish cheese sauce


During the week, when I indulge in a bowl of garden salad and call it dinner, I often think about the difference between guy food and girl food. If you believe that some dishes are not entirely gender-neutral, then you'll understand when I say this roast beef panini with caramelized onions and horseradish cheese sauce has guy food written all over it. I loved every single bite, yes I did, because the combination of beef, onions and horseradish reminds me in the best way of a wood-paneled steak house dining room, where thick cuts of meat arrive on oversized plates, with a baked potato and sour cream. The cheese sauce comes together in seconds from pantry ingredients, and really takes this sandwich over the top.


Roast beef panini with caramelized onions and horseradish cheese sauce

From the pantry, you'll need: sliced bread, onions, olive oil, grated cheese, mayonnaise, bottled prepared horseradish, fresh black pepper.

If you made caramelized onions* in your slow cooker earlier in the week, substitute a few tablespoons of those for the onion listed here. You can save any extra horseradish cheese sauce in the refrigerator for a few days. Makes 2 sandwiches.


1 gigantic or 2 medium onions, thinly sliced*
2 Tbsp olive oil + extra for brushing the panini
1/2 cup mayonnaise (I use Hellmanns)
1/4 cup grated cheese (Cheddar is great)
2 tsp prepared horseradish
Large pinch of fresh black pepper
4 slices of bread
8 slices of roast beef


In a small nonstick frying pan over low heat, combine the onions and 2 tablespoons of olive oil. Cook, stirring occasionally, for 6-7 minutes, until the onions are soft and lightly browned. Remove from heat and set aside.

Stir together the mayonnaise, grated cheese, horseradish and black pepper in a small heat-proof bowl. Microwave for 30 seconds, until the cheese melts. Whisk together until smooth, and set aside.

Heat a panini press (or grill pan), while you assemble the sandwiches. Brush one slice of bread with olive oil, and place it oiled-side down on a plate. Top with a smear of cheese sauce, 2 slices of roast beef, a tablespoon or so of caramelized onions. Smear another slice of bread with cheese sauce, and place sauce-side down on the sandwich. Paint the top with olive oil. Repeat to complete the second sandwich.

Place both sandwiches on your panini press, and cook until the bread is nicely toasted. Cut and serve.

[Printer-friendly recipe.]

More recipes in The Perfect Pantry:
Bacon jam and cheese panini
Horseradish dip
Bacon, lettuce and tomato sandwich with turkey and chipotle mayo
Oven-barbecued brisket
Grandma's beef brisket in the slow cooker

Other recipes that use these pantry ingredients:
Roast beef with blue cheese and apple panini, from Panini Happy
Hot roast beef sandwiches with horseradish cream, from Never Enough Thyme
Italian beef sandwiches, from Andrea Meyers
Cream cheese spread with beetroot and horseradish, from Nami-Nami
Horseradish mashed potatoes, from Fearless Kitchen

Disclosure: The Perfect Pantry earns a few pennies on purchases made through the Amazon.com links in this post. Thank you for supporting this site when you start your shopping here.


I just knew you were going to do something "extra-fabulous" with those gorgeous caramelized onions! Sure enough!

awesome. that looks so good. I feel comfortable endorsing it as a "guy food" for sure.

Alanna, I've been putting these onions on and in everything, but nothing comes close to this sandwich!

Todd, thanks for the "guy food" endorsement. My husband gave it thumbs up, also.

I know what you mean about girl and guy food. Sometimes I feel sorry for my husband because I cook so much for me. Both of us would love this!

If you show a girl how to make caramelized onions in her crock pot, she'll want to make a roast. ;)

Pam, same here, but this is one sandwich we can both enjoy.

Jessica, I hope she'll want to make lots of things with those caramelized onions! I have more posts coming.

Oooh ... This looks so decadent.

Wow! If I had to choose one sandwich to eat every single day it would be this! I love roast beef sandwiches with horseradish and the caramelized onions - and the grilling - just kick it up about ten notches! I love it! Now I am hungry.

CJ, yes indeed!

Jamie, I agree, this is one of those sandwiches we all crave. And it's all about the cheese sauce and onions, so you could make it with grilled chicken, too.

NOW you are speaking my language! I LOVE horseradish sauce! oh my I need some guy food right now!
...with a side of sliced garden fresh tomatoes to complete it!

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