Mix together salsa, mustard, and lime juice. Place in large zip bag and add chicken breasts. Make sure chicken is well coated, Marinate the chicken for at least 30 mins.
Melt butter in large skillet over medium-high heat.
Remove chicken from marinade and add to skillet. Reserve the marinade to add in later.
Brown chicken on both sides, about 10. mins. Add marinade to skillet and cook about 5 more minutes. Chicken should be tender and glazed with the marinade.
Remove chicken from skillet and place on a platter.
Boil marinade over high heat for 1 minute. Add in cilantro and stir.
Serve marinade over chicken. Add a dollop of sour cream, if desired.
Serve and enjoy!