Yuca is as essential to the millions who live in the tropical lowlands of South America as corn is to the people of Central America and Mexico. When encountering the tuber, most Americans don't know where to begin. Here's how to handle it. With a heavy knife, trim off and discard ends from 2 lbs. of yuca. Cut yuca crosswise into 3"–4" sections with a heavy knife. You will see 2 layers of rind: the rough, dark outer surface and an underskin that is pink on one side and white on the other. With the tip of a small, sharp knife, make several cuts along the length of each section, going deep enough to pierce the pink underskin. To peel yuca, work the tip of the knife under this lower layer to detach it from the flesh until you can remove an entire piece. Pare away any stubborn bits. Split each yuca chunk lengthwise; place in a medium saucepan. If the chunks are particularly thick, cut them into small pieces. Cover yuca generously with salted water; bring to a boil. Reduce heat to medium-low and simmer, stirring occasionally, until a small knife easily slips in and out of the yuca's flesh, about 30 minutes. Remove from heat; keep yuca in the water until ready to serve. Just before serving, drain yuca and remove any thin woody cores. Serve with the Huanchaco-Style Fish Stewed in Tomatoes and Chiles and the Grouper Ceviche, or on its own. Serves 4.