Place buttermilk, thyme, garlic, 1 teaspoon salt, and ½ teaspoon cracked black pepper into a mixing bowl and toss together until well combined.
Add potatoes and allow mixture to sit for 15 minutes.
Place flour, onion powder, mustard, paprika, remaining teaspoon salt, and pepper into a shallow dish and stir together.
Spoon about 1/2 cup buttermilk mixture into flour mixture.
In batches transfer potatoes from buttermilk and dredge in flour mixture.
Fill a large, deep skillet with 1 ½ to 2 inches of oil and preheat to 350˚F.
Shake off excess flour from potato slices and transfer to a cooling rack, in a single layer, until all potatoes have been coated.
Fry potatoes in small batches for 6 to 8 minutes or until golden brown and potatoes have cooked through. Drain onto a baking sheet lined with paper towels and a cooling rack and season with salt.
Serve chicken fried potatoes with dipping sauce.