1. Heat oil in a large nonstick skillet over medium-high heat.

2. Add chicken breasts; cook, turning once, until lightly browned.

3. Remove chicken to a plate and set aside.

4. Add onion and garlic to skillet; reduce heat to emdium.

5. Cook until onion is translucent, about 3 minutes; add a tablespoon or two of chicken broth if necessary to avoid burning.

6. Add chicken broth; bring to boil.

7. Whisk in mustard until blended.

8. Return chicken and juices to skillet.

9. Reduce heat to low, cover, and simmer 12-15 minutes until chicken is done; turn chicken once.

10. Transfer chicken to platter; cover with foil to keep warm.

11. Boil sauce in skillet 2-3 minutes to reduce slightly.

12. Put yogurt in a small bowl; whisk in 1/3 cup of hot sauce.

13. Stir yogurt mixture back into sauce in skillet.

14. Simmer until hot, about 1 minute; do not allow to boil.

15. Season with salt and pepper; pour sauce over chicken and serve.