No need to wash the mushrooms. If there is some dirt, just brush or cut them off and discard them.

Trim the ends of the stalks of the mushrooms. Separate stalks from the petals if they are too big. Break apart the big ones into small, even size for more even cooking. Place the mushrooms in a large bowl.

In a small bowl, mix together the salt, ground pepper, garlic powder, and onion powder. Add this to the mushroom and mix well using your hands, making sure that the mushrooms are well seasoned. Then add the cornstarch and flour and mix again to coat completely.

Place the coated mushroom in a strainer (with big holes) or mesh and tap several times to shake off excess breading.

Heat oil in a deep pan or skillet over medium heat. Once the oil is hot add some mushrooms. Do not overcrowd, cook in batches. Do not stir for the first 2-3 minutes. Once it starts to turn golden you can flip or stir for more even cooking until they are golden brown. Transfer the fried mushroom to a cooling rack/dripping rack and cook the next batch.

Once all mushrooms are fried, return the first half to the hot oil to cook for the second time for another minute or two. If you are using a deep fryer or large pan, you can cook them all at the same time just make sure that you use enough oil so as not to overcrowd.

Remove the mushrooms from the oil using a spider ladle or slotted spoon. Transfer to a large bowl lined with paper towels. Place another layer of paper towels on top. Cover the bowl with a plate, then lift and shake around to remove as much oil as possible.

Transfer to a serving dish and serve with spicy vinegar or other desired dip or enjoy on its own.