To get that restaurant-quality, "shatter-crisp" exterior with a fluffy, mashed-potato interior, the secret is the Double-Fry Method combined with a starch-removal step.

1. The Right Potato

Avoid waxy potatoes like Red Bliss or Yukon Gold if you want maximum crunch. You need Russet potatoes (Idaho). They have the highest starch content and the lowest moisture, which is essential for a light, airy center.

2. The Preparation (The "Starch Wash")

• Cut: Slice them into consistent sticks, about 1/4 to 3/8 inch thick.

• Soak: Submerge the cut fries in a bowl of cold water for at least 30 minutes.

• The Secret Ingredient: Add a splash of vinegar to the soaking water. The acid helps the potato's pectin stay intact, preventing the fries from falling apart during the first stage of cooking.

• Dry: This is the most important step. Use a clean kitchen towel to pat them bone dry. Any moisture left on the surface will turn into steam and make the fries soggy.

3. The First Fry (The "Blanch")

• Temperature: Heat your oil (Peanut or Canola) to 325°F (160°C).

• The Goal: You aren't browning them yet; you are cooking the inside until it’s tender.

• Process: Fry them in small batches for about 5–6 minutes. They should look pale and limp but be soft enough to pierce with a fork.

• Rest: Remove them and let them drain on a wire rack for at least 15 minutes.

4. The Second Fry (The "Crisp")

• Temperature: Increase your oil heat to 375°F (190°C).

• The Goal: To create a rigid, golden-brown crust.

• Process: Drop the blanched fries back in for 2–3 minutes. They will turn golden very quickly at this temperature.

5. The Finish

• The Toss: Immediately move them to a metal bowl and toss with fine sea salt while they are still glistening with oil.

• The Serve: Avoid crowding them in a deep bowl where they can "steam" each other. Spread them out to maintain the crunch.