In a large skillet, heat 1 tablespoon olive oil over medium-high heat until smoking. Working in batches if necessary, add meat in a single layer and cook until well-browned on all sides, about 6 to 8 minutes. Transfer to a large plate and repeat with remaining beef if applicable.
Return skillet to medium-high heat and add remaining tablespoon oil, white mushrooms, minced porcini mushrooms, and salt to taste (I like 1/4 teaspoon). Cook, stirring frequently until all liquid has evaporated and mushrooms start to brown, about 7 to 9 minutes.
Add onion and sprinkle with salt (I like 1/4 teaspoon). Continue to cook, stirring frequently, until onion begins to brown and dark bits form on pan bottom, about 6 to 8 minutes.
Stir in garlic, thyme, and flour until vegetables are coated with flour, about 1 minute. Stir in remaining 1 1/2 cups beef broth and porcini soaking liquid, scraping bottom of pan with wooden spoon to loosen browned bits and bring to boil.
Nestle steak pieces into mushroom and onion mixture and add any accumulated juices to skillet. Reduce heat to medium-low and simmer until steak registers 130 degrees on instant-read thermometer, about 3 to 5 minutes.
Season with salt and pepper to taste (I like 1/2 teaspoon salt and 1/4 teaspoon pepper) and sprinkle with parsley. Serve with noodles if desired.