When Isha Gutierrez-Sumner cooks, she’s often swept away by memories of her grandmother, who taught her how to prepare cassava—a tuberous root packed with cyanide. She remembers how her grandmother peeled its brown skin and grated the white flesh. Then, the two of them packed the shredded cassava into a long, snake-like woven tube made from palm fronds, called a ruguma, to hang from the roof. As the sun dried the cassava, the compact tube squeezed out toxins. The next morning, they milled the dried cassava into a fine powder…
