Preheat oven to 350 F. Season both sides of the chicken thighs with salt and pepper. Heat 1 tablespoon of oil over medium-high heat and brown chicken on both sides, working in batches, if necessary, so that the chicken doesn't steam. Remove the chicken and set aside.

Add remaining oil to the same pan, and sauté the onions till translucent, about 5 minutes. Add the mushrooms and cook down for about the same amount of time. Stir in the garlic and cook for one minute, stirring often. Add in the tomato and flour, and cook for about 1 minute, to cook off the flour flavor. Add the dried tarragon. Deglaze the pan with white wine, allowing it to cook, so that the alcohol can burn off. Return the chicken to the pan, and add your chicken stock. Cover, and place in the oven for 45 minutes (30 minutes covered and 15 minutes with the lid removed).

When finished, remove the chicken from the pan and add the mustard and yogurt, and whisk until blended. Return the chicken to the pan, and spoon some of the sauce over the chicken, so that it is well coated. Serve with butter and parsley noodles.

Enjoy!