1. To make filling: Bring a large pot of salted water to a boil. Add the potatoes and cook until tender, 20-30 minutes depending on their size. Peel and cool.
2. Chop parsley and preserved lemon.
3. Mash potatoes using a food mill or a potato riser and add the parsley, preserved lemon, and harissa. Taste and adjust seasoning if needed.
4. To assemble the Brik: Set up oil in the deep fryer. The oil should reach about two-thirds up the pan—more is better, as the Brik will fry faster and retain less oil. When the oil is simmering (not boiling!), it’s ready.
5. Place a malsouka in a shallow dish (this will make it easier to manipulate). Depending on how thin your wrapper is, you may need to double up. Place two to three large spoonful of the filling in the middle of the malsouka. 
6. Using the back of your spoon, make a dent in the filling. Crack the egg and gently place it in the dent. Carefully fold the Brik into a half-moon shape and drop it in the oil.
7. Using a spoon, pour hot oil onto the topside of the Brik, so that it cooks evenly. After about a minute and a half (or until the crust becomes golden brown) remove the Brik. Repeat until you’ve used up all your filling.
8. Serve immediately, with fresh parsley and lemon wedges.

Optional:
• Make the potato filling and place into piping bag.