What You Need
Grate potato and onion on the large holes of a box grater. Working with small handfuls at a time, place the potato mixture into a clean kitchen towel and squeeze all the water from the mixture. Place in a dry medium bowl as done. Season with salt and toss to combine.
Heat the HexClad Hybrid Double Burner Griddle over medium until hot, about 2 minutes. Add 1 tablespoon of the oil and 1 tablespoon of the butter and stir with a spatula until butter is melted, combined, and evenly distributed. Add potato mixture into a thin even layer, using the spatula to combine.
Cook, without turning, until the bottom side is golden, about 5 minutes. Using a metal spatula break the hashbrown into 6 pieces and flip each piece. Drizzle the remaining tablespoon oil and dot the remaining tablespoon butter around the hashbrowns. Cook until hashbrowns are crispy and golden, 6 to 8 minutes more. Remove to a paper towel lined plate and serve warm.