Prepare your dredging station. Combine the plant milk, hot sauce, pickle brine and apple cider vinegar in one bowl, let it sit for 5-10 minutes to form the buttermilk. Make sure it's thick enough to stick to the chick'n, if not, add more vinegar. Combine the flour, cornstarch, baking powder and cajun seasoning in another bowl.
Heat up oil to 375° F either in an electric deep fryer, or a dutch oven with a deep fry thermometer.
If you want to tear up your mushrooms into smaller pieces while the oil heats up, this is a good time to do so!
Once oil is up to 375° F, dredge your mushrooms first in the wet mixture, then dry, and then repeat to double dredge, shaking off any excess flour and batter. Place carefully in oil and let it fry until golden brown. Let it rest on a wire rack. Repeat until all your chick'n is fried.
You can keep the fried mushrooms warm in an oven set to your lowest setting (mine went down to 170° F) or serve immediately (let them cool a bit though, you don't wanna burn your mouth off!)
Serve up however you like, make a Po' Boy, a Popeyes Chick'n Sandwich, Nuggets, whatever you want!
ENJOY!