Cast Iron Steak Tips with Mushroom-Onion Gravy

Adjust oven rack to middle position, place 12-inch cast-iron skillet on rack, and heat oven to 500 degrees. Meanwhile, pat steak tips dry with paper towels and season with salt and pepper.

When oven reaches 500 degrees, remove skillet from oven using potholders and place over medium heat; turn off oven. Being careful of hot skillet handle, add 2 tablespoons oil and heat until just smoking. Brown half of steak tips on all sides, 6 to 8 minutes; transfer to bowl. Repeat with 1 tablespoon oil and remaining steak tips; transfer to bowl.

Add remaining 1 tablespoon oil to fat left in skillet and heat over medium heat until shimmering. Add mushrooms, onion, and ¼ teaspoon salt, cover, and cook, stirring occasionally, until mushrooms have released all their liquid, about 5 minutes. Uncover and continue to cook until liquid has evaporated and vegetables begin to brown, 4 to 6 minutes.

Stir in garlic, tomato paste, and thyme and cook until fragrant, about 30 seconds. Stir in flour and cook for 1 minute. Stir in broth and Worcestershire, scraping up any browned bits and smoothing out any lumps.

Bring gravy to simmer, then stir in browned beef and any accumulated juices. Reduce heat to medium-low and simmer, stirring occasionally, until beef registers 130 to 135 degrees (for medium), 3 to 5 minutes. Off heat, stir in parsley and vinegar and season with salt and pepper to taste. Serve.