Philly Style Mushroom Cheesesteak

Heat the oil in a 10-inch heavy skillet over medium-high heat until very hot but not smoking.

Season the steak on both sides with the salt and pepper. Put the steak in the hot oil and sear for 3 minutes. Turn the steak and cook for another 2 minutes (it will be very rare but will cook more later).

Take the skillet off the heat, transfer the steak to a cutting board, and cover loosely with foil.

Return the skillet to medium heat. Add the mushrooms and onion and cook, stirring occasionally, until they're tender and beginning to brown, about 5 minutes.

Add another 1 tablespoon canola oil if the pan seems dry. Add the scallions and garlic and cook until the scallions are limp, about 1 minute. Loosely cover the skillet and slide it off the heat.

Trim any fat from the sides of the steak and cut the steak into thin (1/8 to 1/4 inch) slices. Add the steak slices, any accumulated juices, and the tomatoes to the mushrooms in the pan. Season with salt and pepper and toss well.

Divide into two loose piles in the skillet. Lay a cheese slice over each pile and cover the skillet to melt the cheese over low heat.

Slide a large metal spatula under one pile of steak, mushrooms, and cheese and drape it over one slice of the toasted bread. Repeat with the other pile and slice of toasted bread.

Serve immediately.

NOTE: If you like the cheese to be browned, run the whole open-faced sandwich under the broiler.