Heat oven to 475 degrees F and arrange rack in top.
Peel potatoes and cut lengthwise into 1/2-inch-wide planks. Cut planks lengthwise into 1/2-inch-wide strips then cut strips in half crosswise. Cover potatoes in hot tap water and let soak for 10 minutes before proceeding.
Meanwhile, combine oil and garlic in a small saucepan and bring to a simmer over medium-low heat. As soon as the mixture is aromatic and the garlic makes a sizzling noise, remove it from the heat and set aside to cool.
When potatoes are done soaking, drain, and thoroughly pat dry with paper towels. Place potatoes on a baking sheet, drizzle with garlic oil, sprinkle with 1 teaspoon of the salt, and turn to coat well. Spread fries out evenly across baking sheet and roast until fries are just beginning to color, about 25 minutes. Using a spatula, scrape sheet to turn fries and continue to roast until crisp on outside, potatoes give way when pierced with a knife, and are golden brown, about 15 minutes more.
Remove fries from oven, season with remaining 1 teaspoon of salt, and serve immediately.