Fish and Yuca Stew with Pickled Onions

Preparation

1. Cook yuca:

   Step 1

   If using fresh yuca, remove peel and pink flesh using a vegetable peeler. Cover fresh or frozen yuca with salted cold water in a 3- to 4-quart saucepan. Bring to a boil, then simmer, covered, until yuca begins to split, 15 to 20 minutes. Transfer yuca with a slotted spoon to a cutting board, reserving water in pan. Cut into 1-inch wedges, pulling out and discarding tough core. Return yuca to cooking water and simmer, covered, until tender and completely translucent, 15 to 25 minutes more.

2. Make pickled onions while yuca cooks:

   Step 2

   Cover onion with boiling-hot water in a heatproof bowl and let stand 15 minutes. Drain onion and return to bowl. Add lime juice and salt, tossing to coat, and let stand at least 5 minutes before serving.

3. Make fish stew while yuca finishes cooking:

   Step 3

   Bring water, tomatoes, cilantro, cumin, and 3/4 teaspoon salt to a boil in a 3- to 4-quart heavy saucepan. Reduce heat and simmer, covered, 5 minutes. Toss fish with remaining 3/4 teaspoon salt and stir into broth. Cook, uncovered, over moderate heat, stirring occasionally, until fish is just cooked through, 3 to 5 minutes. 3Drain yuca and divide among 4 large soup bowls. Ladle fish stew over yuca and top with some of pickled onions.