In a large bowl, combine flour, sugar, salt, onion powder and instant yeast.
Make a well and add the milk, egg and olive oil. Whisk well with a fork and then combine the dry ingredients into the wet to get a smooth batter. Cover and keep aside to prove in a warm place or one hour until the batter is bubbly and risen.
To the well-risen batter, add all the remaining ingredients. Break any clumps of mashed potatoes with a fork. Combine well until you get a smooth batter. At this point you can either get on with the waffle baking or refrigerate (upto 12 hours) until you need to make the waffles. You can prepare this at night and refrigerate overnight. Do leave it out for an hour or so before making the waffles.
Preheat the waffle maker. Brush some oil on the top and bottom sections.
Ladle little over half cup batter per waffle (this is for the waffle maker I use). Close the waffle maker and cook until golden brown on both sides.
Serve hot with ketchup.
Notes
You can cut each waffle into bite sized pieces and serve them as finger food along with a dipping sauce.
Add a fried or poached egg on top and a salad on the side to make a full meal out of these waffles.
Prepare a batch of the waffles. Freeze and store in resealable bags (label with date so you use them up in a month or so). Bake in the oven for 4-5 minutes until thawed and heated when you want to serve them.