Onion may be sliced like a blossom by cutting the top 1/4 off, the top has the stem. Then peel and be very careful to leave the root intact. Carefully slice from the top of the onion down but stop about 1/2" before you get to the root, taking care not to cut through the root. Slice the rest of the onion like a pie into many servings.
When complete soak onion in cold ice water for 1/2 hours so the onion's petals will start to open up and bloom.
Drain onion and dip in flour mixture and dust well. Dip onion then in buttermilk and back in flour mixture.
Place in hot oil and fry until golden. Oil should cover onion. When done drain well and place on plate and cut center out of onion so the petals may easily be removed.