How to Make It
Bring 10 cups water to a boil in a large stockpot over high; reduce heat to medium-low, and maintain a simmer.
Meanwhile, use a mandoline fitted with a waffle blade or use a wave waffle cutter to cut potatoes into waffle-shaped slices. Drop potato slices, in batches, into simmering water, and cook, stirring occasionally and adjusting heat if necessary to maintain a simmer, until translucent, about 3 minutes. Using a spider or slotted spoon, gently remove potato slices from water, and arrange in a single layer on a wire rack set inside a rimmed baking sheet. Let stand until cool, about 25 minutes.
While potatoes cool, heat canola oil in a large, deep Dutch oven over medium-high to 400°F. Working in batches, fry potato slices until outside of potato is firm, about 30 seconds. Transfer potatoes to a wire rack set inside a baking sheet to drain. Transfer drained potatoes to a parchment paper–lined baking sheet to cool, and freeze until frozen, 30 to 45 minutes. Reduce heat to low, keeping oil warm until ready to use again.
Stir together berbere and salt in a small bowl. Set aside.
Reheat oil to 400°F over medium. Working in batches, fry potatoes, stirring often, until golden brown, about 2 minutes. (Adjust heat between batches to maintain temperature as needed.)
Using a spider or slotted spoon, remove fries from oil, and drain on a wire rack over a baking sheet. Sprinkle spice mixture over hot fries.