Clean and tear oyster mushrooms into bite-sized pieces. Set aside.
Make an assembly line. Grab three bowls. Add 1 cup of flour plus two teaspoons of Old Bay seasoning to the first bowl, the hemp milk to the second bowl and 2 cups of panko plus two teaspoons of Old Bay seasoning to the third bowl.
Working in batches, dip the oyster mushrooms into the flour mixture, then dredge in the hemp milk. Last, roll the mushrooms in the panko making sure to coat them completely. Set the mushrooms on a wire rack that has been placed overtop of a baking sheet. Repeat until all the mushrooms are coated.
Bake the mushrooms at 400° F for 20 minutes or until the mushrooms are golden and crispy.
While the mushrooms bake, make the remoulade. Set aside.
To assemble the po'boys, split and toast four mini loaves of French bread (hoagie rolls or large hot dog buns can be used as a substitute). Top each roll with lettuce, tomato and pickles and then the mushrooms. Dollop the po'boys with generous amounts of remoulade sauce. Enjoy while hot.