Scrub the potatoes clean and rinse under water. Remove any nubby or sprouting spots then place them in a large dutch oven or soup pot and fill with water until the potatoes are submerged in one inch of water.
Add 1 tablespoon of kosher salt to the water and bring to a boil, uncovered, over high heat. Continue to boil for 20-25 minutes, or until the potatoes are easily pierced with a fork. It may take longer depending on the size of the potatoes.
Right before the potatoes are done, preheat the air fryer to 400°F for 5 minutes.
When the potatoes are done, drain them in a colander and wait a few minutes until they’re cool enough to handle. Transfer them to a cutting board and use a potato masher or the back of a measuring cup and flatten the potatoes to 1/2 inch thick. Repeat this process with all of the potatoes. Let the potatoes rest for 5 minutes so some of the steam escapes to make them more crispy.
Transfer them to the basket of the preheated air fryer. Drizzle with melted butter or vegan butter then drizzle them with olive oil. Sprinkle with garlic powder and onion powder.
Air fry at 400°F for 15-20 minutes, or until they're golden brown and crispy. Remove from the oven and sprinkle with fresh herbs, pepper, red pepper flakes or Parmesan cheese.