1. Melt the 2 sticks of butter in a small saucepan over medium heat. Remove from heat and whisk in 1/3 cup of mustard.
2. Cut chicken breasts into four even strips lengthwise and flatten slightly with a meat pounder. Dip the pieces in the butter -mustard mixture and lightly season them with salt and pepper. Coat the chicken with the ground pecans. Press pecans with your hands because the chicken needs to be coated heavily.
3. Preheat even to 200 degrees.
4. In a large skillet, melt the remaining butter and add the oil. When hot, saute` the chicken until browned, aproximately 3 minutes for each side.
5. As the chicken is done, remove from pan and place in a baking dish to keep warm in the oven. (At this point you may refrigerate the chicken and warm it later in 350 degree oven)
6. After all the chicken is cooked, pour of the butter and oil and discard any remaining burnt pieces of pecans. Deglaze the pan with the sour cream, scrape up all the browned bits and pieces. Whisk in remaining mustard and season to taste.
7. To serve, spoon a little sauce over each chicken piece. If you wish, you may add a roasted pecan half.