When I cleared out my mother‘s apartment after she moved to an assisted living home a few years ago, I scavenged a few things from her kitchen: the palm-sized rock from the shores of the Indian Ocean that was used to grind spices, a set of stainless steel bowls, a wooden press for making string hoppers, a Sri Lankan noodle dish. Her trusty knife she‘d used for decades, however, went into the donation pile. It was a steak knife with a black plastic handle and a serrated edge that had never seen a sharpener. You can buy a dozen of...