If you want to avoid deep frying, you can cook the rolls in a hot oven (200-250° C / 400-475° F), being sure to turn them so they brown well on all sides.

1. Cook the potatoes in boiling salted water and mash them with a fork.
2. Finely chop the onion and parsley.
3. Cook the onions slightly in 1 or 2 tbsp. water. Add the parsley just before turning off the heat.
4. Hard boil 2 eggs and chop them finely.
5. Grate the Parmesan and Gruyere; finely dice half the preserved lemon.
6. Combine all the ingredients and add 1 or 2 raw eggs. Season with salt and pepper. The mixture should not be liquid.
7. Cut the brick sheets in half and place 1 teaspoonful of filling on each one; roll up to form a finger. Repeat with the remaining ingredients to form 24 fingers.
8. Heat the oil over medium heat in a deep skillet and fry the rolls. Remove them when nicely browned and drain well in a strainer lined with paper towels before serving.
9. Serve on a bed of lettuce with lemon wedges.