Cook egg noodles per package instructions until al dente (mine only take about 5 minutes). When the noodles are cooked, drain and set aside.
While the noodles cook, heat 1 tablespoon oil in a large skillet or Dutch oven over medium-high heat. Cook the ground beef 6–8 minutes until browned and cooked through, seasoning with 1/2 teaspoon Kosher salt and 1/4 teaspoon pepper as it cooks. Transfer the beef to a plate; do not wipe out the pan.
If there's enough fat to coat the bottom of the pot, add the mushrooms. But if the pot looks dry, add 1 tablespoon of oil. Cook the mushrooms with the remaining 1/2 teaspoon of Kosher salt and pepper. Cook until softened and liquid has released, about 5 minutes.
Once the mushrooms are cooked, add the beef back to the pot. Sprinkle with the thyme and garlic. Cook 1 minute until fragrant.
Sprinkle the flour over the beef and mushrooms, stir to coat, and cook for a minute or two until the raw flour smell is gone.
Pour in the beef broth. Stir and scrape up any bits at the bottom of the pan. Bring the pot to a simmer and stir until the sauce thickens, about 1–2 minutes.
Turn off the heat, and stir in the soy sauce and sour cream. Give the sauce a taste and adjust the salt or pepper if needed.
Add the cooked egg noodles to the pot and stir to coat. Keep in mind the noodles will soak up the sauce as it sits. You could also serve the sauce and noodles separately.
Serve hot, and enjoy!