French-Ish Dip Panini With Pastrami, Sharp Cheeses, and Beer-Mustard Onions

A French dip-inspired panini that leans into pastrami

The French dip is a sandwich worth celebrating: savory, rich, and built for anyone who loves a hot, melty bite with a side of au jus for dunking. While it’s often associated with familiar essentials—beef, cheese, bread, and that deeply flavorful dipping broth—this “French-ish dip” panini takes the idea in a different direction by swapping in pastrami and pressing everything together on rye.

Recipe developer Patterson Watkins describes pastrami as “the perfect sandwich protein,” pointing to its peppery, slightly smoky, slightly salty character. The concept here is to build on two beloved sandwich traditions at once: the classic pastrami-and-rye pairing and the dunkable satisfaction of a French dip. The result is a hot sandwich that’s bold by design, then carefully balanced so it doesn’t become overwhelming.

What makes this version different

This isn’t just a French dip with a different meat. The entire sandwich is designed around contrast—salty cured beef, sharp cheeses, and a sweet-tangy onion topping that’s caramelized and simmered in dark beer. Everything is layered on rye, then pressed so the exterior turns crisp while the interior becomes molten and cohesive.

Watkins leans into strong flavors on purpose. Pastrami has a distinctive cured profile, and she pairs it with three sharp cheeses that can stand up to it. To keep the sandwich from feeling one-note, the onions are cooked down until jammy, then finished with mustard and honey for a sweet-and-tangy counterpoint. It’s a combination that aims for richness without losing balance.

Ingredients you’ll need

The recipe breaks into three parts: warming the pastrami in a seasoned broth (which becomes your au jus), making the beer-mustard onions, and assembling/pressing the panini.

• 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 building the panini: rye bread, butter, Cooper Sharp cheese, sharp cheddar cheese, fontina

Watkins specifically chose Cooper Sharp, sharp cheddar, and fontina to create a “sharp balance” against the sweet onions and smoky-peppery pastrami. If you want to vary the cheese, she notes that Swiss, Gruyère, mild cheddar, or Provolone can also work.

Step-by-step: how to make the French-ish dip panini

Below is the full method, organized so you can move smoothly from pot to skillet to press. The timing is designed so the onions cook while the pastrami warms in the broth.

• 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.
• Meanwhile, melt the butter in a large skillet over medium heat.
• Once melted, add the onions, and saute 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.
• 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.
• 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.
• Ladle the au jus between serving cups and serve alongside the sandwiches for dipping.

Why pressing matters (and how to do it without a panini press)

A panini press can make this recipe feel straightforward, but it’s not required. Watkins emphasizes that paninis are “fun to have” but not essential. Her workaround is practical: use a grill pan to create the ridges and a heavy skillet—she uses a small cast-iron skillet—as the weight that functions like a press.

If you don’t have a grill pan, the same idea still applies. Two cast-iron skillets can do the job: the larger one becomes the cooking surface, and the smaller one becomes the weight on top. The key is consistent pressure rather than occasional flattening with a spatula.

Watkins explains that these sandwiches are meant to be pressed with a steady weight, not “merely smushed.” That weight helps create what makes a panini feel like a panini: a crisp exterior and a hot, melty interior where the cheese and fillings fuse together. You can still toast the sandwich without added weight, but you’ll miss the signature crunch-and-melt contrast this method is built around.

Managing salt: why the broth is low-sodium

Pastrami brings a lot of flavor—and a lot of salt. Watkins notes that pastrami is cured in a “pretty salty bath,” which is why it tends to be saltier than many other deli meats. In a sandwich that also includes cheese, that salt can quickly dominate if you’re not careful.

That’s why the recipe starts with low-sodium beef broth for the au jus. The idea is to keep the dipping liquid flavorful but controlled, since it’s much easier to add salt later than it is to fix a broth that’s already too salty. This is also why you won’t see extra salt added elsewhere in the method; between the pastrami and cheese, the sandwich has plenty of seasoning built in.

What the dark beer contributes to the onions

The onion topping is more than caramelized onions—it’s a mustardy, sweet-tangy condiment with extra depth from dark beer. After the onions soften and brown, the pan is deglazed with stout or porter and simmered until the beer is nearly evaporated. That reduction step concentrates flavor and helps the onions move toward a jammy texture.

Watkins describes dark beer as a “delightful ingredient” for cooking because it can bring hints of toast, nuts, cocoa, and caramel. Those notes are meant to complement the mustard and honey added at the end, creating a topping that can hold its own against sharp cheeses and smoky-peppery pastrami.

Any neutral stout or porter works here, and the alcohol cooks off during simmering, leaving the flavor behind. For an option that avoids alcohol entirely while aiming for a similar profile, Watkins recommends using a combination of root beer and coffee instead.

Assembly notes: building layers for melt and structure

The order of ingredients is intentional. Starting with buttered rye creates the base for browning and crispness. Cooper Sharp goes down first, then the hot pastrami, then the onion mixture, and finally the cheddar and fontina before the top slice of bread goes on.

Two details matter during assembly. First, let excess au jus drip off the pastrami before it hits the bread; you want the sandwich cohesive, not soggy. Second, reserve the au jus in the pot—this is what turns the panini into a dip sandwich at the table, giving each bite the option of extra savory broth.

Serving: a panini you can actually dunk

Once pressed and toasted, the sandwiches are served with au jus ladled into individual cups. That small step changes the experience: instead of relying only on cheese and onions for moisture, you get the classic French dip ritual—dip, bite, repeat—while still enjoying the rye-and-pastrami personality that defines this version.

The final result is a hot sandwich that’s intentionally bold: pastrami for peppery smoke and salt, sharp cheeses for richness, and beer-caramelized mustard onions to bring sweetness and tang. Pressing delivers the crisp exterior and melty interior, and the au jus on the side ties everything back to the French dip tradition that inspired it.