Thinly slice the onion and place the slices in a bowl or jar. Soak them in the vegan buttermilk for at least 10 minutes. You can also leave these covered in the fridge for up to 12-24 hours.
Heat up your frying oil over medium-high heat. Add enough to have a layer about 1/2-1 inch thick in the pan. You will know it is ready and hot enough when a small amount of flour sizzles when tossed in the oil.
Mix together the salt, pepper, flour, and garlic powder in a mixing bowl or shallow dish. Drain the onion slices and toss them in the flour mix.
Fry the onion slices in batches if needed so as not to crowd the pan. You don't want them overlapping too much. Fry for several minutes until golden brown.
Drain on a plate with paper towels. Use them as salad toppings, on sandwiches, pasta, or on your favorite dish. They can be kept in an airtight container in the fridge for a day or two, but they are best the same day when they are crispiest.
