Season the chicken breast with oregano, garlic salt, and salt and pepper. Vacuum seal the chicken breast and then place it in your sous vide at 150ºF for one hour.
Once the chicken breast is cooked, pull it out of the sous vide and into an ice bath. Pull the chicken breast out of the vacuum sealed bag and pat it dry.
Bring a non stick pan to medium-high heat. Add 1 or 2 tbsp of cooking oil (vegetable oil works well) and 1 tbsp of butter. Once the butter melts add the chicken breast to the pan. Cook on both sides for 1 to 2 minutes on each side until the chicken breast turns into a nice brown color. Take the chicken breast out of the pan and set it aside. Cut the garlic cloves set in half (height wise) and place both halves face down on the pan along with another tbsp of butter. Once the garlic cloves start turning lightly brown, add the mustard and stir, quickly followed by the chicken stock. Stir and reduce for 5 to 7 minutes on high heat until the sauce thickens to desired consistency.
When the sauce is ready remove the garlic cloves and serve. Serve with a nice quinoa, pasta, risotto, or mashed potatoes. It really goes well with a lot of things.