Hand shred Lion's Mane Mushroom into small pieces resembling texture of flakey crab.
In large bowl, combine egg, mayonnaise, onion, Worcestershire sauce, old bay seasoning, Dijon mustard, parsley (finely chopped), salt and pepper. Mix until fully incorporated.
Mix in Lion's Mane Mushroom until fully incorporated.
Mix in Panko breadcrumbs until fully incorporated.
Form mixture into 3-4 equal size round flat patties (about ½ to ¾ inch thick).
Heat oil in sauté pan on medium/high heat.
Alternatively bake at 350 for 15-20 mins, flipping halfway.
Cook patties for approximately 2-3 minutes per side. Should be golden brown and cooked throughout.
Add optional garnish, squeeze of lemon.