Preheat the oven to 250°F. Place a cooling rack on top of a baking sheet, and then place that setup in the oven.
In a large bowl, whisk together the tapioca flour, garlic powder, onion powder, salt, pepper, olive oil, and water until evenly combined. Add the green onions, dill, and mashed potatoes to the bowl. Using a spatula, stir and fold everything together until evenly combined.
Preheat your waffle iron to the highest setting.
Once the waffle iron is heated, open it up and give the grates a spray with your oil spray. Measure out a slightly heaped ⅓ cup of the batter and drop it into the middle of the waffle iron. Close the lid of the waffle iron with some pressure to flatten out the potato mixture inside.
When the timer goes off on your waffle iron, open it up and check. The waffle should be deep golden brown. If you need to initiate another cooking cycle to get to this point, go ahead. Once you have it sufficiently browned, remove it from the iron with a fork and either serve it immediately OR transfer the waffle to the rack + baking sheet setup in the oven.
Repeat this process with the remaining waffle mixture. Enjoy the waffles hot with scrambled tofu, avocado, salsa, hot sauce, lightly dressed greens, or whatever else you may enjoy!