Start by cooking the frozen white pearl onions according to the package instructions; however, only cook them halfway.
While those are cooking, prepare the batter. Grab three small shallow bowls. In one bowl, add half of the flour. With the second bowl, pour the liquid egg whites. In the third, add the other half of the flour, the cornmeal, panko and the seasonings, stirring to combine.
When the pearl onions are ready (halfway cooked), drain off any excess liquid.
Place the white pearl onions in the bowl with the flour, you may want to do just a few at a time, and cover with flour.
Then, add them to the bowl of liquid egg whites, covering them in egg whites. Again, you may want to do just a few at a time.
Then, add them to the bowl with all of the batter ingredients, covering them in batter. Again, you may want to do just a few at a time.
Then, place them in a greased air fryer. Air fry at 350 degrees for 3 minutes, then open the air fryer and spray the onions with cooking spray.
Air fry for another 3 minutes. Then, open the air fryer, shake the onions, spray again with cooking spray, then continue air frying. Air fry for another 3 minutes.
Then, open the air fryer, shake the onions, spray again with cooking spray, then continue air frying until your desired crispness, another 3-5 minutes. In total, this will be about 12-15 minutes; however, be sure to check on them as time starts to run out.
While those are cooking, prepare the sauce. Mix all the ingredients for the sauce together in a bowl. Store in the fridge until the roasted pearl onions are ready, to allow the flavors to form together.