- Cut onions into 1/2-inch slices, and separate into rings.
- Set aside.
- Whisk together flour and next 4 ingredients until smooth.
- Pour oil to a depth of 2 inches into a Dutch oven; heat to 375°.
- Dip onion rings in batter, coating well.
- Fry, a few rings at a time, until golden.
- Drain on paper towels.
- Serve immediately.