Heat 2 tablespoons oil in a large skillet over medium heat. Add chicken and season with half of salt, pepper, and thyme. Cook for 5 minutes then flip chicken over and sprinkle with remaining salt, pepper, and thyme. Cook an additional 5 minutes or until browned and completely cooked through. Transfer chicken to a plate and cover to keep warm.

Add remaining oil and then add onion and garlic to skillet and saute for 1 to 2 minutes until lightly browned. Whisk in the broth, vinegar, maple syrup, and Dijon mustard. Bring to a boil then reduce heat to medium-low. Cook at a low boil for about 3 or 4 minutes until sauce has reduced a bit and is syrupy. Remove skillet from the heat. Return cooked chicken to pan, nestling it into the sauce. Spoon some of the sauce over chicken and serve.