Philly Steak Sandwich Recipe

Slice the steak very thinly across the grain into bite-sized strips if not pre-sliced. Pat the slices dry with paper towels.

Peel and thinly slice the onion. Core, seed, and thinly slice the green pepper into strips. Clean mushrooms with a damp towel and slice them thinly.

Lay bacon slices on a plate or tray ready for cooking. Split the 7" sub buns and spread mayonnaise inside each half.

Fry bacon

In a large skillet over medium heat, cook bacon until crisp, about 6–8 minutes, turning occasionally. Remove bacon to a paper-towel-lined plate and reserve 1 tablespoon of bacon fat in the pan (discard excess or save for another use). When cool, chop or crumble bacon into bite-size pieces.

Return the skillet to medium-high heat and add 1 tablespoon of vegetable oil and 1 tablespoon of butter. When butter is melted and foamy, add the sliced onion and green pepper. Cook, stirring occasionally, until softened and beginning to brown, about 6–8 minutes.

Add the sliced mushrooms to the skillet and continue cooking until mushrooms release their moisture and everything is browned, about 4–5 more minutes. Season the vegetables lightly with a pinch of salt and pepper. Transfer the cooked vegetables to a plate and set aside.

If needed, add the reserved tablespoon of bacon fat or an additional 1 tablespoon oil to the skillet and heat over high. Season the steak slices with 1 teaspoon salt, 1/2 teaspoon black pepper, and 1/2 teaspoon garlic powder; toss to coat.

Working quickly in a single layer (cook in two batches if necessary so meat doesn't steam), add the steak to the hot skillet and sear, stirring and flipping, until just browned and cooked through, about 2–3 minutes. Remove from heat.

Return the cooked vegetables and chopped bacon to the pan with the steak and toss together gently over low heat for 1 minute to combine and warm everything through. Adjust seasoning to taste with additional salt and pepper if needed.

Heat a clean skillet or griddle over medium heat. Spread the inside of each bun with a thin layer of softened butter and place buttered-side-down on the hot skillet to toast until golden, about 1–2 minutes.

Divide the steak-vegetable mixture evenly between the two toasted bottoms of the buns. Top each with two slices of Swiss cheese. Cover the skillet with a lid or tent with foil for 1–2 minutes to allow the cheese to melt.

Place the top bun on each sandwich and press gently. Slice sandwiches in half if desired and serve immediately while hot.