How do I find a Lawyer that handles Probate Litigation in California?

I live in Ore4gon. I just found out one week ago that my Step Sister passed away. Her will is lodged in the Sacramento Superior Court in accordance with the Calif. probate code. She gave the house and contents away to a friend. She disinherited her brother in her will. Her will was made 10 months before her passing from metastasized uterine cancer. I do not know when she was diagnosed with the cancer. Our last conversation was in the summer of 2016 and she stated that her brother and I would get the house when she died. My father passed away almost three years ago and he stated in his will that my now deceased sister, myself - Dad's natural son and heir, his grandson and stepson(the disinherited brother). We, all, were on good terms before she no longer answered or returned calls. Something is wrong here. We need help. An Attorney here in Oregon said that I should talk to a Probate Litigation Attorney. The lady that holds the will is willing to give "some stuff" to my nephew this week.