Chop the onion, slice mushrooms, and mince garlic. Bring your chosen starch (egg noodles, potatoes, or rice) to a simmer.

Heat a large skillet over medium-high heat. Add the ground beef, breaking it up with a spatula, and cook until mostly browned (about 6–8 minutes). Drain excess fat, if desired.

Push beef to one side and add the chopped onion. Cook for 3–4 minutes until translucent, then stir in minced garlic and cook for an additional 30 seconds.

Add the sliced mushrooms and sauté until they release liquid and brown slightly, about 5 minutes.

Sprinkle the flour over the beef and vegetables, stirring to coat. Cook for 1 minute to remove the raw flour taste.

Gradually pour in the beef broth while stirring to avoid lumps. Bring to a gentle simmer and cook until sauce slightly thickens, about 3–5 minutes.

Remove from heat and stir in the sour cream until smooth. Season with salt and pepper to taste, avoiding boiling after adding sour cream.

Spoon the stroganoff over warmed egg noodles, mashed potatoes, or rice. Garnish with chopped parsley or paprika if desired.