Sauté a large onion in 1 tablespoon of olive oil or ghee over medium heat. When the chopped onion is translucent, add sliced mushrooms. turn the heat up and continue cooking until mushrooms begin to brown, stirring occasionally to prevent burning, about 5-7 minutes. Transfer to a separate plate and keep aside.
Cut chicken breasts into small pieces or strips. In the same pan, heat 1 tablespoon of olive oil or ghee, add the chicken, season with 1/2 teaspoon of salt and 1/4 teaspoon of pepper and continue to cook over medium high heat until pink color is no longer visible, about 10-15 minutes. Add sautéed mushrooms and stir.
Add finely chopped pickles to the pan.
Season with 1/4 teaspoon of black pepper and mix in tomato paste and yellow mustard, Stir well and cook for 2-3 minutes.
Mix in sour cream or it's alternative and thoroughly combine everything. Continue to cook on low heat to prevent sour cream separation and wait until the sauce thickens, approximately 5-7 minutes. Taste the sauce and season with salt if necessary.
Finally, garnish with parsley and dill, mix and serve immediately.
It pairs well with mashed potatoes, zucchini noodles, cauliflower rice or over greens of your choice. I like to serve it over arugula or chopped kale.