Heat olive oil in a skillet over medium heat.
Add chopped onions and sauté until translucent.
Stir in minced garlic and cook for 1 minute.
Add sliced chicken and cook until browned on all sides.
Toss in the sliced mushrooms and cook until softened.
Sprinkle flour over the chicken and mix well to coat.
Gradually pour in the chicken broth, stirring constantly.
Bring to a simmer and let it thicken for about 5 minutes.
Reduce heat and stir in sour cream until well combined.
Season with salt and pepper, and garnish with fresh parsley.