Knead all the ingredients together into a soft and flexible dough. Cover and let it rise for an hour, or until doubled in size.
Divide the dough into balls and shape them into oval rolls as shown in the video. You can also shape them into regular hot dog rolls. Place each roll on a parchment paper square, cover and let rise for about 20 minutes.
Fill ½ a pot with oil and heat it up over medium-high heat (the oil is ready at 355-375 °F).
Add each roll to the pot with the parchment paper and release it using kitchen tongs. Fry on both sides until golden. Remove from the oil and set aside to cool off for 5 minutes on a baking rack or a plate with paper towel.
Combine the potatoes, eggs, pickles and tuna in a bowl.
Cut each roll open. Spread 1 teaspoon of harissa, add 2 tablespoons of filling and serve!