Peel the plantains and cut them into chunks.
In a large pot, bring water to a boil. Add the plantain chunks and cook until tender, about 20-25 minutes.
Drain the cooked plantains and return them to the pot.
Mash the plantains with a potato masher until smooth. You can add a little water or milk if needed to achieve the desired consistency.
In a small pan, heat vegetable oil over medium heat. Add the chopped onion and minced garlic, and cook until softened and fragrant.
Stir the onion and garlic mixture into the mashed plantains. Add salt to taste and mix well.
Enjoy your meal!