Heat 3/4 cup of water in a 2-cup liquid measuring cup in the microwave until hot, not boiling.
Add Better than Bouillon and whisk until dissolved. Set aside.
In a small blender or food processor (See Notes), add the garlic, celery, 1 Tbsp chopped onion, and 2 Tbsp of the beef broth. Pulse until smooth. Set aside.
Season the meat with salt, pepper, and paprika. Add 1/2 tsp oil into a small frying pan on medium heat. Add beef and cook for 5 minutes, stirring. Place cooked meat into a small saucepan. Set aside.
Heat 1/2 tsp oil in the same frying pan on medium heat. Add the remaining onion and cook for 3 minutes. Add the mushrooms and 2 Tbsp of the beef broth and cook for 3 more minutes. Place in the saucepan with the beef.
On medium heat, in the frying pan, place 2 Tbsp butter. When melted, add 2 Tbsp of flour, whisking the mixture for 30-60 seconds until it is bubbly.
Add the remaining beef broth, tomato paste, and Worcestershire sauce. Continue to whisk until smooth. This mixture will be thick.
Add the blended onion, garlic, and celery to the sauce and whisk. Cook for 2 more minutes. Add more beef broth if needed. Check for salt and pepper. Adjust to taste. Add the sauce to the meat and mushrooms and stir. Heat on medium-low for 8 – 10 minutes.
While the stroganoff is cooking, prepare your noodles according to the package directions using salted water. Drain.
Add 2 Tbsp sour cream and mix it into the stroganoff. The stroganoff is ready. Garnish with the remaining sour cream and parsley.