Preheat oven to 325ºF. In a large bowl, soak the potatoes in salted water for 15 minutes. Drain, pat dry and arrange them on a baking sheet. Spray the potatoes with cooking spray and bake for 10 minutes. Season with salt and pepper. Increase the oven temperature to 475ºF and bake, turning once, until very crisp and golden-brown all over, about 30 minutes.
In a small skillet, melt the butter over medium heat. Add the garlic, then remove from the heat and stir in the parsley. Pour over the baked fries.
Preheat a cast-iron skillet over medium-high heat. While the pan is heating up, whisk together the vinegar, EVOO and sugar. Add the cabbage, season with celery salt and pepper. Toss and let sit while you make the burgers.