Beef Medallions with Caramelized Pan Sauce

2 pounds beef tenderloin, trimmed, cut into 8 (4-ounce) medallions

salt and freshly ground black pepper to taste

1 tablespoon vegetable oil

8 sliced fresh mushrooms

1 tablespoon unsalted butter

1 tablespoon olive oil

1 pinch salt

½ cup tomato sauce

⅓ cup Marsala wine

1 cup chicken broth

2 teaspoons chopped fresh oregano

1 ½ tablespoons chilled unsalted butter, cut into cubes

Season beef medallions with salt and pepper to taste and set aside.

Heat vegetable oil in a skillet over high heat. Cook beef until browned, about 2 minutes per side. Remove beef to a warm plate.

Reduce heat to medium; cook and stir mushrooms, 1 tablespoon unsalted butter, olive oil, and a pinch of salt in the skillet until mushrooms are very well browned, about 10 minutes.

Mix in tomato sauce; cook and stir until tomato sauce thickens, about 5 minutes.

Pour in Marsala wine and increase heat to high. Cook, scraping browned bits from bottom of skillet. Once most of the wine has evaporated, stir in broth and bring to a boil; cook and stir until broth mixture has reduced by half, about 5 minutes.

Reduce heat to low and return beef to broth mixture; simmer until beef is cooked to medium-rare, about 2 to 3 minutes. Transfer beef to serving plates.

Remove skillet from heat. Cook and stir 1 1/2 tablespoons butter and oregano into the sauce until butter melts. Taste for seasoning and adjust if necessary.

Spoon sauce over beef and serve immediately.