First, prepare the batter by mixing the cornstarch, flour, and seasonings in a bowl until well blended. Add the beer and mix well.
Next, prepare the seasoned flour in a second bowl by combining and mixing the ingredients.
To prepare the onion, cut about 3/4 of an inch off the top and peel. Cut 12 to 16 vertical wedges into the onion, but do not cut through the bottom root end. Remove about 1 inch of the petals from the center of the onion. You may want to separate the onion petals slightly, but do not do this too much or you will destroy the onion.
Heat your deep-fryer to 375°-400°.
Dip each onion in the seasoned flour. Remove excess flour by shaking the onion gently. Separate the petals to coat it thoroughly with batter. Then dip the onion into the batter and back into the flour mixture again.
Gently place in fryer basket and deep-fry for 1.5 minutes. Turn over and fry an additional 1.5 minutes. Drain on paper towels.
Place the fried onion upright in a shallow bowl and remove center core with circular cutter or apple corer. Repeat these steps for each onion.
Serve with your homemade dipping sauce.