Step 1

Bring a medium pot of water to a boil. Peel plantains, cut in half lengthwise and cut each half into 4 pieces crosswise. Add the plantains to the boiling water; cover and cook, adjusting the heat as needed to prevent boiling over, until the plantains are completely tender, about 30 minutes. Using a slotted spoon, transfer the plantains from the water to a large bowl. Do not discard the cooking water.

Step 2

Meanwhile, heat 1 teaspoon oil in a large nonstick skillet over medium-high heat. Add onion; cook, stirring, for 1 minute. Stir in vinegar and 1/8 teaspoon salt; cook, stirring, for 1 minute more. Transfer to a small bowl. Wipe out the skillet.

Step 3

Add 2 tablespoons oil and the remaining ½ teaspoon salt to the plantains in the bowl. Mash with a potato masher, slowly adding ¾ cup of the reserved cooking water, until smooth and creamy. Add more water for a creamier consistency, if desired.

Step 4

Heat the remaining 1 tablespoon oil in the skillet over medium-high heat. Carefully crack eggs, 1 at a time, into the pan; cook, using a rubber spatula to keep the eggs separate, until the whites are completely cooked but the yolks are still slightly runny, 2 to 3 minutes.

Step 5

Divide the plantain mash among 4 plates and top each with a fried egg and some of the onion.