Pastrami, Caramelized Onion, and Gruyère Sandwich

This pastrami, caramelized onion, and Gruyère sandwich combines peppery meat, sweet onions, and nutty cheese in this easy, satisfying meal.

A pastrami, caramelized onion, and Gruyère sandwich on a pretzel roll sliced in half with a sprig of thyme lying beside it on a wooden cutting board.

Onion rye, sliced sourdough, or challah would all be great breads for this sandwich. At Macrina, we often feature it on our pretzel knot roll, a fairly dense roll made with the addition of a little rye flour, then topped with coarse salt, poppy seeds, and sesame seeds. The combination of these flavors with the American favorite delicacy of thinly sliced peppery pastrami plus sweet caramelized onions and nutty Gruyère cheese is terrific.–Leslie Mackie

LC A Proper Pastrami Sandwich Note

Not every slice of meat slapped between a couple slices of bread qualifies as a sammich. But this one does. (Don’t even get us started on that annoying trend of referring to a sandwich as a sammie. Sheesh.) In addition to qualifying as supper, this hearty little number also does a darn good job of qualifying as a brown-bag lunch, one that’ll at least give you something to look forward to all morning.

Pastrami Sandwich

  • Quick Glance
  • (1)
  • 25 M
  • 45 M
  • Makes 4 sandwiches
5/5 - 1 reviews
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  • For the caramelized onions
  • For the mustard aioli
  • For the sandwiches


Make the caramelized onions

Melt the butter in a large nonstick skillet over medium-low heat. Add the onions and toss to coat. Cook until the onions have softened, about 5 minutes, and add the thyme and red pepper flakes, if using. Continue caramelizing the onions, stirring them frequently so they brown evenly, for up to 60 minutes or more. (If the heat is too hot, the onions will burn, so slow it down and take some time to enjoy the process.) Season to taste with salt. Transfer the onions to a large bowl and set aside.

Make the mustard aioli

Whisk the egg yolk, garlic, lemon juice, and mustard in a medium bowl to thoroughly combine. Start adding the canola oil, just a few drops at a time, whisking constantly, until the mixture begins to emulsify. As it thickens, continue adding the oil in a slow stream, making sure each addition is thoroughly blended before adding more. Season to taste with salt. Cover the aioli and refrigerate until needed.

Assemble the sandwiches

Position a rack in the center of the oven and preheat to 350°F (176°C). Line a rimmed baking sheet with parchment paper.

Cut each roll in half horizontally. Butter the cut sides of the rolls and place them, cut side down, on the baking sheet. Toast the rolls in the oven for 3 to 5 minutes, until the butter is melted and the rolls are warm.

Flip each roll over so that the cut side is up. Spread each side with some mustard aioli. Place equal amounts pastrami on the bottom half of each roll, folding it up to only slightly overhang. Next, divvy the caramelized onions among the sandwiches, layering them on the pastrami. Place the Gruyère on the top halves of the rolls. Return the sandwiches, still open-faced, to the oven for 5 minutes, or until the cheese is melted and the pastrami is warm to the touch.

Sandwich the halves together and, if desired, cut on the diagonal with a serrated knife. You can take it from here.

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Recipe Testers Reviews

Each of the individual elements in this sandwich is delicious enough on its own, but together, they’re heavenly, albeit rich! I used a homemade rye bread with a nice crunchy crust and a tight crumb. I didn’t add hot pepper flakes to the caramelized onion because I wanted a purely sweet flavor. The aioli had the perfect amount of garlic—enough so you could taste it in the background but not so much that it overwhelmed the other flavors in the sandwich. These sandwiches were surprisingly rich because of all the strong flavors—I think you could make little mini 1- or 2-bite sandwiches as a perfect hors d’oeuvre! I’ll definitely be making these again when I’m in the mood for a decadent sandwich.

We enjoyed every part of this sandwich for lunch. We found the pretzel knot rolls at Whole Foods and they were the perfect combination of crisp outside and soft inside. I made the onions the day before to speed up my day-of assembly. The aioli (my first attempt ever) was easy to make and came together flawlessly, and, of course, how could you go wrong with pastrami and Gruyère? My only wish was that our pretzel rolls were slightly larger—one was a little small for lunch and yet 2 sandwiches would’ve been too much. Finally, I think these sandwiches could be made in advance and wrapped up to serve later. They’d be just as good at room temp as they are right out of the oven.

This is a yummy sandwich. We made it on good rye bread and had it for supper. The size of the bread or roll makes a difference here. Our slices of bread were on the small side so we each had two overstuffed sandwiches and enjoyed them to the last bite!

I omitted the red pepper flakes in our sandwiches for the sake of the young eaters. The caramelization of the onions was easy to do and affords the cook the time to make the mustard aioli. When everything is done you can let the aioli flavors meld a little or serve it right up. A quick dinner.

What a lovely, gooey, yummy sandwich! Gruyère, peppered pastrami, and caramelized onions make the world go around as far as this tester is concerned. I loved the bite of the pepper, the richness of the Gruyère, and the sweet onions all trying to escape the toasted onion bread I used to surround it. Then add in that wonderful mustard aioli and you really did it to me. Some people would say this is just a sandwich, but me, I say this is dinner for company.


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  1. Is it possible to get the pretzel knot recipe? The other parts of the ‘recipe’ are too easy, but I couldn’t figure out the bread recipe on my own. Thanks!

    1. Deanna, we received permission from the publisher to reprint the sandwich recipe, but not the pretzel knot rolls recipe. But hang in there, let me inquire again. If we can acquire the recipe, I’ll have our testers give it a twirl and then I’ll be back in touch….

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