How to Make It
Place yuca in a large saucepan and add cold water to cover by 2 inches. Add vinegar and 1 1/2 teaspoons salt. Bring to a boil over medium-high; reduce heat to medium and simmer until yuca splits open and is soft throughout, 30 to 45 minutes, depending on thickness of yuca.
Meanwhile, heat oil in a large skillet over medium-high until shimmering. Add garlic and cook, stirring, until garlic begins to soften and turn golden, about 20 seconds. Reduce heat to medium; add onion and cook, stirring occasionally, until onion is light golden and crisp-tender, about 10 minutes. Season with remaining 1 teaspoon salt.
Drain yuca in a colander. Gently separate the chunks into large pieces and remove the tough core if necessary. Arrange yuca on a platter or in a wide serving bowl. Pour the hot oil, garlic, and onions over the yuca. Serve immediately.