Clean and cut the squid: Remove the innards & skin, then cut the body into thin long strips. Cut the tentacles so there are 2 or 3 tentacles to each piece. You can refer to my ojingeo bokkeum recipe to learn how to clean a squid if you don't don't know how (steps 2-4).
Peel and cut a Korean sweet potato into 1 cm thick discs.
Pat the squid as dry as possible with paper towels, then coat in 2 tbsp cake flour or ap flour so the wet batter will stick to it.
Make the wet batter:
First mix together cake flour, corn starch, baking powder, sea salt, garlic powder, and white pepper. Cake flour has the lowest percentage of gluten and will be the best option for a light, crispy batter. You can use all purpose flour if you don't have cake flour, but it won't be quite as light & crispy.
Mix in 1 beaten egg and cold club soda. Mix with chopsticks but do not overmix. Little clumps are ok. Add less club soda if you want a thicker batter, more if it needs to be thinner (thinner is better for light & crispy).
Coat the veggies & squid in the batter and shake off any excess.
Fry at 350ºF. Immediately after adding to the fryer, drizzle over a little batter and use your chopsticks & a fine mesh strainer to hold it together and flip over. Drizzle again and flip over. A lot of the batter will scatter around the oil- that's fine just collect it with the strainer and discard so it doesn't burn. You can skip the drizzle step for the perilla leaf, it doesn't need more crunch. If you don't care for extra crunchiness around each piece of twigim, you can skip the drizzle step for all of them.
Keep your oil clean and collect any leftover batter between each fry
Repeat in batches (you can do 3-4 at a time). I fry the squid last to minimize any cross contamination issues. Here are the approximate frying times for each:Squid: 1-2 minutes (optional to double fry)Korean pepper: 1 minute Sweet potato: 3 minutes Perilla leaf: 30-40 seconds
Rest on a cooling rack Note: for extra extra crunch, you can double fry! I did this for the squid and it turned out GREAT.
To Reheat:This batter will stay crispy for a long time. Even after a day left on the counter it was still crispy! You can store these in the refrigerator for up to 3 days. I think the best way to reheat them is to air fry at 375ºF for 3-4 minutes. You can also reheat in the oven.