Add the pickle juice to a ziplock back or a container and put the fillets in to marinade. Place in the fridge so the fillets will defrost, and let it marinade overnight or for about 8 hours.
Heat the peanut oil in a skillet over medium heat while you prepare the pieces to fry. Look for the oil to shimmer to know it's hot.
To prepare to bread the fillets, pat the fillets dry and cut them into about 4 nugget-sized pieces.
For dredging, in one bowl mix the dijon and water to thin out the mustard to act as the wet part. You may need more of this mix depending on how the dredging goes.
In another bowl, add the flour, paprika, onion powder, garlic powder, mustard powder, salt, and pepper. Mix to combine.
To dredge the Quorn, first coat a piece in the dijon mix, and then add then put into the flour mix. Pat the piece to make sure it's fully covered. Then, repeat in the wet ingredients and dry ingredients for two layers. Make sure you pat the flour into the nugget well.
When the pieces are breaded, add to the hot oil. If you put a piece in and it does not sizzle, pull the piece out and wait until the oil is hotter. If the oil is sputtering too much, turn down the heat.
Add the piece, and cook about 3 minutes on each size until golden brown. Use a slotted spoon to remove the pieces from the oil and place on a plate to cool.
Serve immediately on biscuits or alone.