Place the yucca into a pan and fill with enough water to cover. Stir in salt. Bring to a boil over medium-high heat, cover, and cook until tender, about 15 minutes. Drain, and place yucca on a serving plate.
Meanwhile, place the olive oil, onion, garlic, and lemon juice into a pan. Cook over medium heat about 5 minutes. Pour the hot olive oil mixture over the yucca, and serve immediately.