Creating his own take on the classic jazz-with-strings album was the initial impetus for Joshua Redman’s Walking Shadows, a collection of ballads, both vintage and contemporary, that can be as eloquently moody and restless in feel as they are hauntingly beautiful and serene. With his friend and frequent collaborator, the pianist Brad Mehldau, on board as producer—the first time Mehldau has assumed that role for a project other than one of his own—Redman has retooled a familiar formula.