Cut the unpeeled plantain into a little under ½ inch [1 cm] thick slices (about 8 slices per plantain).This step is if you are going to boil them, if you are going to microwave them, do not cut or peel them.
2. Precook the plantains
Boiled: Place the plantain into a pot and cover with water (plus about an extra inch over it). Boil over medium-high heat for about 20-25 minutes, starting counting from the time it breaks the boil. The plantain slices should be cooked completely, but still firm, if they are even a little raw in the center they will break when crushed. Carefully peel and crush one, if it flattens but not breaks, it's cooked (it will be soft and flexible, that's fine). Once cooked through, remove from the water and pat with a paper towel to whisk away excess moisture. Peel the slices using a tong to avoid burning yourself. Proceed to step 4.Microwave: Place the plantain, unpeeled, in the microwave, and cook for 3.5-5 minutes (try with 3 ½ minutes, check for doneness and cook more if needed). The peel will break, and you can remove it with tongs to avoid burning yourself. Cut into a little under ½. Proceed to step 4.
3. Flatten
If you have a tostonera (Amazon affiliate link) flatten the slices between two pieces of parchment or wax paper, so the plantain doesn't stick to the tostonera (you may grease the paper with a bit of oil for extra precaution).If you don't have a tostonera, flatten using the bottom of a glass jar, putting the plantain slices between two pieces of paper as described above. In either case, it's best if the slices are very thin (around 3 mm [⅛ "]).
4. Season
Brush the flattened slices with olive oil. Sprinkle with salt and garlic powder.
5. How to cook tostones
In air fryer: Preheat the air fryer to 400 ºF [200ºC]. Place the slices of plantain in the air fryer bowl, making sure they are not piled up and return bowl to the air fryer.Cook for 15 minutes or until they turn a light golden color and are crispy around the edges.In the oven: Preheat the oven to 400 ºF [200 ºC]. Place the slices of plantain on a wire rack, making sure they are not piled.Cook for 15 to 20 minutes or until they turn a light golden color and are crispy around the edges.
Video
Notes
It's important that you do not crowd the air fryer basket. Arrange them in a single layer, and if you do not have enough space, it's best to make them in separate batches.