Combine garlic and 2 cups water in a medium bowl; set aside
Heat ½ cup oil in a large skillet, preferably cast iron, over medium-high. Working in 3 batches, fry plantains in a single layer, turning once, until tender and golden all over, about 5 minutes. Transfer to paper towels to drain. Pour out oil; discard. Reserve skillet
Gently press down on plantains one at a time with the flat side of a chef’s knife or wooden spoon to flatten slightly. Transfer to bowl with reserved garlic water and let soak 5 minutes
Remove plantains from garlic water and pat dry with paper towels. Heat remaining ½ cup oil in reserved skillet over medium-high. Fry plantains again, turning once, until deep golden brown, 6–8 minutes. Transfer to fresh paper towels to drain; sprinkle with salt