Prep the potatoes. Scrub and peel the russets (peel optional). Cut into even sticks, about 1/3 inch thick. Consistent size helps them cook evenly.

Soak to remove starch. Place the cut potatoes in a bowl of cold water and soak for 20–30 minutes. This reduces surface starch and helps the fries crisp instead of turning gummy.

Dry thoroughly. Drain and spread the potatoes on a clean towel. Pat very dry. Moisture is the enemy of crispiness.

Coat and season. In a large bowl, toss the fries with 2 tablespoons olive oil, 1 tablespoon cornstarch (if using), 1 teaspoon salt, 1/2 teaspoon black pepper, and 1/2 teaspoon garlic powder. The cornstarch creates a thin, crunchy shell.

Choose your method: Oven or Air Fryer. Oven: Preheat to 450°F (232°C). Line two sheet pans with parchment. Spread fries in a single layer with space between. Bake 15 minutes, flip, then bake 12–15 minutes more, until deeply golden and crisp.

Air Fryer: Preheat to 380°F (193°C). Air fry in batches for 14–18 minutes, shaking the basket halfway through. Don’t overcrowd; space equals crisp.

Make the garlic oil-butter. While the fries cook, warm 1 tablespoon olive oil and 2 tablespoons butter in a small pan over low heat. Add minced garlic and a pinch of red pepper flakes. Cook 60–90 seconds, stirring, until fragrant but not browned. Remove from heat.

Toss with flavor. As soon as the fries are done, transfer to a big bowl. Pour over the warm garlic butter, toss, then immediately add Parmesan, parsley, and lemon zest. Toss again so the cheese melts slightly and sticks.

Taste and finish. Add a final pinch of salt and black pepper to taste. Serve hot while they’re at peak crispiness.