Mix together cold water and 1/4 tsp sea salt in a bowl until the salt is dissolved. Add the sliced plantains and let it soak for 30 minutes.
Drain plantains and pat dry with a paper towel.
Add avocado oil to a cast iron pan over medium heat.
Add plantains one by one making sure they are not touching each other so it cooks evenly. Fry for 5 minutes.
Flip to the other side and fry for another 5 minutes.
Remove from the pan and drain on paper towels.
Grab one piece of fried plantain and using the flat bottom of a small bowl or drinking glass, gently press onto the plantain in a clockwise motion until it is flattened to about 1/4" thick. Do this for the rest of the fried plantains.
On the same pan that is kept on medium heat, fry the flattened plantains for a second time, about 2 minutes each side.
Remove from heat and drain on paper towels.
Season with some coarse ground sea salt.
While the tostones are cooling, melt ghee in a small saucepan over low heat.
Once the ghee is hot, add minced garlic and cook it for 2 minutes.
Stir frequently so that it does not burn and stick to the bottom.
Remove from heat and drizzle on top of the tostones or serve on the side as a dip.