Step 1

Slice the ends off of the plantains. Make three vertical cuts along the length of the plantain, only making sure that you are cutting into the skin. Under cold running water, using your fingers or a butter knife (the tip of your knife works best) to remove the skins. With a sharp knife, cut each plantain into ¾-inch to 1-inch slices. Set aside.

Step 2

Mix the 3 cups of water and salt together (just until the salt is dissolved). Place the thick rounds in the salt water for ½ hour or no less than 10 minutes.

Step 3

In the meantime, prepare the Ajillo: Using a mortar and pestle, pound the salt and garlic together. Add in the cilantro and break it down until it's pasty. Once that's done, mix in the olive oil and adjust the salt to taste. Alternatively, you can use a food processor or finely chop the cilantro, grate the garlic, and mix everything together.

Step 4

To make the Mayo Ketchup Sauce: In a small bowl, combine ketchup, mayonaisse, and garlic, and set aside (this will be good for up to 3 days, covered, in the refrigerator).

Step 5

Remove the plantain slices from the water and dry them well with paper towel or a kitchen towel. This will prevent oil splatters.

Step 6

Heat the oil on medium heat (oil should be around 325ºF / 160ºC). In batches, place the plantains in the hot oil and cook for about 4 minutes on each side until golden brown. Repeat with all the plantains, then remove from the oil and drain.

Step 7

Place one of the fried plantains between two pieces of parchment paper. Using the flat side of a meat mallet, the bottom of a mug, bottom of a glass, or bottom of a heavy sauce pan or small cast-iron skillet, smash the plantain down until it is evenly flattened (roughly 1/4-inch / 2/3-cm thick. Repeat with the rest of the fried plantains.

Step 8

While smashing all of the plantains, crank the heat to medium-high heat (the oil should register 350ºF / 180ºC to 360ºF / 190ºC). After all of the plantains have been smashed, fry them once again until golden brown and crispy. Immediately salt them as they come out of the oil.

Step 9

Serve Tostones with Ajillo and or Mayo Ketchup Sauce.