01 - Pat the sliced onions dry with paper towels to remove excess moisture.
02 - In a large bowl, combine flour, cornstarch, salt, black pepper, and cayenne pepper.
03 - Toss the onions in the flour mixture, ensuring they are well coated; shake off any excess flour.
04 - Heat vegetable oil in a heavy-bottomed pot to 350°F (175°C).
05 - Fry the coated onions in batches for 2 to 3 minutes, stirring occasionally, until golden brown and crispy.
06 - Remove fried onions with a slotted spoon and drain on paper towels.
07 - Allow onions to cool completely before storing in an airtight container for up to 3 days.