Rinse the okra and slice each pod lengthwise. Place the sliced okra in a large bowl with enough water to completely cover. Add the vinegar and mix well. Let stand for 15 minutes, stirring every 5 minutes. Drain and rinse the sliced okra. Pat dry with paper towels.
Place the prepared okra in a large bowl and drizzle over the olive oil. Sprinkle in the salt and garlic powder. Toss until all pods are coated evenly with the oil and seasonings.
Put the seasoned okra on a foil-lined baking sheet. Bake for 20 minutes, turning halfway through the cooking time.
Remove from the oven and lower the temperature to 170 degrees. When the oven has cooled to 170, return the pan to the oven and prop the door open. Continue to bake for 2-3 hours or until crisp. Remove from the oven and cool for at least 30 minutes.