2 TBSP butter
Melt the butter and oil in a large sauté pan with a lid. Add the chicken pieces and cook for about 5 minutes, until brown. Put the browned chicken pieces on a paper towel lined plate and season well with salt and pepper.
Meanwhile, strip the leaves from the remaining tarragon, chop them finely, and set aside. Add the stems to the cooking chicken and vegetable mixture.
Remove the chicken and mushrooms from the pan and set aside. It is ok if you have a little of the veggies with the Chicken. This won't happen if you use bigger chicken pieces, but I wanted smaller ones and it turned out very tasty.