Position racks onto the upper and lower third of the oven and preheat to 450°F Cover one baking sheet with aluminum foil and place on lower rack so it heats up.
Slice potato into 1/4-inch thick rounds and toss with olive oil. Mix thyme, garlic powder, salt and cornstarch together and toss evenly with potatoes. Place on hot baking sheet and on the bottom rack in the oven. Cook for 30 min, flipping the potato slices half way through.
For Fish: Mix mayo, Old Bay, cayenne pepper, lemon juice and water in a small bowl. Add more water, one teaspoon at a time, until you have a smooth and lightly thickened consistency. Place the flour and the panko breadcrumbs in separate shallow bowls and dip cod strips into flour, removing excess flour. Then dip into the mayonnaise mixture and finally in the breadcrumbs, making sure to press the panko into the fish so that it adheres.
Place fish strips on a baking sheet lined with parchment paper and spray with PAM non-stick spray. Place on the top rack of the oven and cook for 6-10 minutes, depending on the thickness of the fish, until fully cooked. If needed, broil for 1 minute so that the fish are browned.
Remove fish and chips from oven and serve immediately.