New York Panini Recipe

Prepare onions

Thinly slice the yellow onion. Heat a 10" skillet over medium heat and add 1 tablespoon butter and 1 teaspoon olive oil. Add the sliced onion and sauté, stirring occasionally, until softened and translucent and beginning to caramelize, about 8–10 minutes. Season with 1/4 teaspoon salt and a pinch of black pepper toward the end. Remove from pan and set aside.

Prepare bread and tomato

Slice the Italian loaf lengthwise to make a top and bottom. If the loaf is very thick, split further so each sandwich portion is about 1"–1.5" thick. Lightly butter the outer faces of the bread (about 1 tablespoon butter total), and if using Dijon mustard, spread it thinly on the inside of one half. Thinly slice the tomato into 1/4" rounds and season the tomato slices lightly with the remaining salt and a pinch of pepper.

Assemble sandwich

On the bottom half of the bread, layer half the Swiss cheese (2 slices) so there is cheese under the beef, then pile 4 oz of thinly sliced roast beef evenly over the cheese. Scatter half the sautéed onions over the roast beef, then arrange tomato slices on top. Add the remaining roast beef and the remaining 2 Swiss slices on top of the tomato (cheese on top helps with melting). Place the top half of the bread on the sandwich.

Panini press / skillet finishing

Preheat a panini press or a large skillet/griddle over medium-high heat. If using a skillet, place a heavy second skillet or a foil-wrapped brick on top for even pressing. Brush the outside of the sandwich lightly with a little melted butter (or place buttered side down on the hot surface). Place the sandwich on the press or skillet and cook until the bread is golden and crisp and the cheese is melted, about 3–5 minutes in a panini press or 4–6 minutes per side in a skillet with pressing. If using a skillet and pressing method, flip once and re-press to ensure even toasting.

Rest and slice

Remove the sandwich from the heat and let rest for 1–2 minutes to let the cheese set slightly. Slice the sandwich into two or three portions on a diagonal and transfer to plates.

Combine the mayonnaise, ketchup, prepared horseradish, Worcestershire sauce, dill pickle relish, white wine vinegar, paprika, 1/4 teaspoon salt, and 1/8 teaspoon black pepper in a small bowl. Whisk until smooth and well combined. Taste and adjust seasoning, adding a touch more horseradish for heat or more vinegar for brightness. Chill in the refrigerator for at least 10 minutes to meld flavors.

Serve about 2–3 tablespoons of Russian dressing per sandwich on the side for dipping or spread a thin layer inside the sandwich if preferred.