Slice the onions as thinly as you can. You can use a mandolin slicer to make things easier.
Transfer the sliced onions into a bowl and cover it with buttermilk.
Meanwhile, prepare the flour and spice mixture and set it aside on a plate.
Drain the excess buttermilk and toss the onions to the flour mixture, making sure everything is well coated.
Transfer the onions to the pot with the heated oil or a deep fryer and let them cook until they’re crispy and golden brown. Use a slotted spoon to get them out and let them rest for a few minutes before you serve them.
Notes
Remember to heat the oil well before you add the onions in. You can test if they’re hot enough by adding an onion string inside, and checking if it rises up and starts to bubble.
If you’re making these tobacco onions in a big batch, don’t overcrowd the pot with too many onions. Instead, fry the onions in batches to ensure that they’re all crispy and golden.
Remember not to let the onions brown up too much- get them out as they start turning golden brown and let them sit on a plate lined with paper towels to soak up all the excess oil.
You can also use a saucepan or a skillet to fry the onions if you want to.