French-Ish Dip Pastrami Panini With Sharp Cheeses and Beer-Caramelized Onions
A French dip-inspired panini that leans into pastrami
The French dip is an ultra-savory hot sandwich built around a simple but deeply satisfying idea: warm beef, melted cheese, bread sturdy enough to hold it all, and a cup of au jus for dunking. In this “French-ish dip” panini approach, the familiar structure remains—hot meat, cheese, bread, and dipping broth—but the flavor profile shifts in a deliberate way. Instead of sticking strictly to roast beef and French bread, this version brings deli-sliced pastrami into the spotlight and swaps in rye bread, echoing a classic pastrami-on-rye pairing while keeping the dip-friendly spirit intact.
The result is a sandwich designed for people who love rich, hot, pressed paninis: a crisp exterior, a melty interior, and a side of au jus that turns each bite into something even more decadent. The pastrami contributes a peppery, slightly smoky, slightly salty character, while a trio of sharp cheeses intensifies the savory depth. To keep those bold elements from becoming overwhelming, the sandwich is finished with a sweet-tangy onion topping—caramelized and simmered in dark beer, then enriched with mustards and honey until jammy.
What makes this sandwich different
This panini is built around a few intentional choices that distinguish it from a standard hot pastrami sandwich or a traditional French dip.
Pastrami as the main protein: Rather than roast beef, the sandwich uses deli-sliced pastrami warmed in a seasoned broth. That broth doubles as the au jus served on the side.
Three sharp cheeses: Cooper Sharp cheese, sharp cheddar, and fontina are layered to create a bold, melty filling. The sharpness is meant to stand up to the pastrami’s cured, peppery profile.
Beer-caramelized mustard onions: Onions are sautéed, deglazed with dark beer, and cooked down with Dijon mustard, grainy mustard, and honey until they become a spreadable, jam-like topping.
Rye bread and a pressed finish: Everything is stacked on rye and pressed panini-style for a crisp, crunchy exterior and a cohesive, melted center.
Ingredients you’ll need
The recipe breaks into three parts: warming the pastrami and creating the au jus, cooking the onions, and assembling/pressing the sandwiches.
For the hot pastrami and au jus: low-sodium beef broth, prepared horseradish, minced garlic, fresh chopped rosemary, fresh chopped thyme, deli-sliced pastrami.
For the beer and mustard onions: salted butter, sliced yellow onion, dark beer (stout or porter), Dijon mustard, grainy mustard, honey.
For assembling the panini: rye bread, butter, Cooper Sharp cheese, sharp cheddar cheese, fontina.
While the recipe is designed around that specific trio of cheeses, there is flexibility if you need it. Other options mentioned as workable substitutes include Swiss, Gruyère, mild cheddar, or Provolone. The overall goal is to keep the cheese melty and flavorful enough to match the pastrami and onions.
Step-by-step: how to make the French-ish dip panini
This method is straightforward, but it helps to think of it as a sequence: simmer the broth, warm the pastrami, cook the onions until jammy, then build and press the sandwiches.
1) Build the au jus base and warm the pastrami
Place the broth, horseradish, garlic, rosemary, and thyme in a large pot. Stir to combine and bring to a simmer over medium heat.
Once simmering, add the pastrami to the pot.
Reduce the heat to low, cover, and cook for 15 minutes.
This step does two jobs at once: it heats the pastrami gently and creates a seasoned dipping broth to serve alongside the finished sandwiches. When it’s time to assemble, you’ll let excess au jus drip off the pastrami before layering it onto the bread, then reserve the remaining liquid for dipping.
2) Make the beer-caramelized mustard onions
Meanwhile, melt the butter in a large skillet over medium heat.
Once melted, add the onions, and sauté them until they begin to soften and brown, about 5 minutes.
Deglaze the skillet with beer, stir to combine with the onions, and bring to a simmer.
Simmer until the beer has almost completely evaporated, about 10 minutes.
Add the Dijon mustard, grain mustard, and honey to the skillet and stir to combine.
Continue to cook for 2 minutes until the onions become jammy. Remove from the heat and set aside.
The goal here is a topping that is both sweet and tangy, with the dark beer contributing toasty, nutty, caramel-like notes. By simmering until the beer nearly evaporates, you concentrate flavor while moving the onions toward a spreadable texture that won’t slip out of the sandwich when pressed.
3) Assemble the sandwiches
Place bread slices on a sheet of wax paper and spread butter over one side.
Flip 4 of the bread slices over, butter side down.
Divide the Cooper Sharp cheese between the 4 slices.
Top the cheese with hot pastrami (let any excess au jus drip off the pastrami before transferring to the bread). Reserve the au jus.
Top the pastrami with the onion mixture, spreading it out evenly.
Top the onions with the cheddar and fontina cheese slices.
Cap the sandwiches with the remaining bread slices, butter side-up.
Layering matters in a pressed sandwich. Starting with cheese on the bottom helps create a melty “base” that can hug the pastrami, while the second layer of cheese on top reinforces the gooey interior once heat and pressure are applied.
4) Press and toast
Preheat a panini press, panini pan, or grill pan over medium heat.
Once hot, add the sandwiches. Firmly and evenly press the sandwiches (using either a sandwich press or a heavyweight pot or pan).
Toast for 2 minutes or until golden brown on one side. Flip, press, and repeat on the other side until the sandwiches are toasty and the cheese has melted.
5) Serve with au jus for dipping
Ladle the au jus between serving cups and serve alongside the sandwiches for dipping.
That final step is what keeps the “French-ish dip” identity front and center. Even though the sandwich leans into pastrami-on-rye territory, the reserved broth brings back the classic dunkable element.
No panini press? You can still make it work
A panini press is convenient, but it isn’t required. The key is consistent weight rather than simply flattening the sandwich with a spatula. A grill pan paired with a heavy skillet can mimic the effect of a press: the grill pan provides the hot surface, while the weight encourages even contact for browning and helps the cheese melt into the layers.
If you don’t have a grill pan, two cast-iron skillets can do the job—one larger skillet for cooking and a smaller one on top for pressing. The point of the weight is to create the signature panini contrast: a crisp, crunchy exterior with a hot, melty interior. Without that steady pressure, the sandwich can still be tasty, but it won’t develop the same cohesive texture or the same level of exterior crispness.
Why low-sodium broth matters with pastrami
Pastrami is known for being saltier than many other deli meats because it’s cured in a salty brine. That saltiness is part of its appeal, but it can easily push a sandwich into over-seasoned territory—especially when you add cheese and a dipping broth.
Using low-sodium beef broth for the au jus is a practical way to keep the final dish balanced. It gives you room to build flavor with horseradish, garlic, and herbs without compounding salt levels. The approach also explains why the recipe doesn’t call for extra salt: between the cured meat and the cheeses, additional seasoning generally isn’t necessary.
What the dark beer contributes (and an alcohol-free option)
Dark beer plays a specific role in the onion topping. Used to deglaze the pan and simmer down with the onions, it brings hints of toast, nuts, cocoa, and caramel—notes that complement both the mustard and the pastrami’s smoky-peppery edge. A neutral stout or porter works well for this purpose, and the alcohol cooks off during the simmer, leaving behind the flavor characteristics rather than the bite of alcohol.
If you want to avoid alcohol entirely while keeping a similar flavor direction, an alternative suggested for retaining that general profile is a combination of root beer and coffee. The idea is to preserve the dark, caramel-like sweetness and roasted complexity that the stout or porter would otherwise provide.
Serving notes and simple ways to keep it balanced
Because this sandwich is intentionally rich—pastrami, three cheeses, buttery rye, and a sweet-tangy onion topping—small handling choices can make the eating experience cleaner and more enjoyable without changing the recipe.
Let excess au jus drip off the pastrami before building: This keeps the bread from getting soggy before it hits the heat.
Spread the onions evenly: A consistent layer helps the sandwich press uniformly and ensures each bite gets some of the sweet-tangy topping.
Press with steady weight: The goal is even browning and a well-melted interior, not an unevenly smashed sandwich.
Serve the au jus in individual cups: It’s easier to dip and helps keep the sandwich crisp between bites.
In the end, this French-ish dip panini is about combining familiar comforts—deli pastrami on rye and the dunkable pleasure of a French dip—into one hot, pressed sandwich. With sharp cheeses to match the cured beef, jammy beer-mustard onions to balance the intensity, and a reserved au jus for dipping, it’s a cohesive, savory meal built for anyone who believes the best sandwiches are the ones served hot and eaten with both hands.