Special equipment: a deep-fry thermometer
For the Southwest fry seasoning: In a small mixing bowl, combine the cumin, granulated garlic, onion powder, smoked paprika, salt, granulated sugar, superfine sugar, chili powder and pepper. Reserve.
For the fries: Fill a large bowl with 8 cups water and the white vinegar. Add the yucca fries and soak for 30 minutes to remove the starch.
Heat the canola oil in a Dutch oven to 300 degrees F.
Bring 6 quarts water and the salt to a boil in a large stockpot. Add the yucca fries and cook until tender and almost translucent, about 6 minutes. Remove from the water with a slotted spoon and place on a clean towel to drain; allow the yucca fries to cool.
Divide the yucca fries into 3 batches. Place the first batch in the hot oil. Blanch for 2 minutes, remove from the oil and transfer to a cooling rack set over a baking sheet to drain excess fat. Repeat with the remaining fries in 2 batches.
Bring the canola oil up to 360 degrees F. Again working in 3 batches, fry the yucca fries until golden brown and crispy, about 3 minutes. Remove from the hot oil with a slotted spoon and place on a paper towel-lined plate. Repeat with the remaining fries in 2 batches. Season the fries with the Southwest fry seasoning. Serve immediately.