Season the Chicken: Start by seasoning the chicken cubes with salt and pepper. Sprinkle flour over the chicken and toss until lightly coated. This helps the sauce thicken later.
Brown the Chicken: Heat olive oil in a large skillet over medium heat. Add chicken in a single layer and cook until lightly golden on all sides. Transfer to a plate and set aside.
Build the Base: Melt butter in the same skillet. Add chopped onion and cook until soft and lightly golden. Stir often to avoid burning.
Add Mushrooms and Garlic: Add sliced mushrooms and cook until they release moisture and turn tender. Stir in garlic and cook briefly until fragrant.
Deglaze the Pan: Pour in white wine and stir, scraping up any browned bits from the pan. Let it simmer until slightly reduced and mellow.
Create the Sauce: Add chicken broth and bring to a gentle simmer. Return the chicken to the skillet and cook until fully tender.
Finish with Cream and Dill: Lower the heat and stir in sour cream until smooth. Add chopped dill and gently mix. Let everything warm through without boiling.
