Fred Hersch will perform two shows in San Francisco this weekend: a free solo concert and conversation at the Community Music Center on Friday and a concert at Herbst Theatre with his new Pocket Orchestra Saturday night. He spoke with the San Francisco Chronicle about his recent triumph over a number of life-threatening illnesses and his return to the stage. "Hersch, who plays jazz with uncommon fluency, feeling and invention," says the Chronicle, "has recovered, regaining his strength through intense physical therapy and getting back to the affirming business of making music."