Ashford & Simpson, whose first duo performance took place in 1972 at Lincoln Center’s Soul at the Center festival, crafted some of pop music’s most indelible hits: “Ain’t No Mountain High Enough,” “Reach Out and Touch (Somebody’s Hand),” “I’m Every Woman,” and “Solid (as a Rock).” Simpson pays a heartfelt tribute to her late partner in art and in life with the help of talented collaborators drawn from their Upper West Side hotspot, Sugar Bar.