The South African soprano was astounded when her coaches in the young artist program at La Scala told her to study the role of Lucia de Lammermoor. “I could barely sing a high C,” she says now – but also, as she asked her teachers, “Who looks like me and sings this repertoire?” (Kathleen Battle was not a star in 1980s and ’90s South Africa.) Here, she tells – and shows – Anthony Tommasini how she came to master the quintessential coloratura star vehicle.