In the first 1938 edition of “Larousse Gastronomique,” an encyclopedic tome on gastronomy, editor Prosper Montagné advised treating and cooking rhubarb’s leaves as you would spinach. While the effects may well have proved fatal (high concentrations of oxalic acid render the leaves toxic) and left me wondering, “Did they have recipe testers back then?” Montagné may have been on to something. For many of us, it’s hard to imagine rhubarb without a generous amount of sugar to take the edge off its sharp taste.