How to Make It
In a medium bowl, combine the tuna, scallions, capers, parsley, olive oil and harissa. Season with salt and pepper and mix gently.
On a work surface, make 2 stacks of 3 phyllo sheets each. Cut each stack crosswise into four 4-by-12-inch strips. Keep the phyllo dough covered with a damp kitchen towel. Place a heaping 1/4 cup of the tuna filling at the end of a strip closest to you. Brush the edge of the other end with the beaten egg. Fold the corner of the phyllo over the filling to form a triangle. Continue folding the triangle up and over itself until you reach the end of the phyllo strip; press to adhere. Repeat with the remaining phyllo strips, filling and beaten egg.
In a large cast-iron skillet, heat 1/4 inch of canola oil until it shimmers. Fry 4 of the phyllo triangles over moderately low heat, turning occasionally, until golden and crisp, 3 to 4 minutes. Transfer the briks to a paper towel-lined plate to drain. Repeat with the 4 remaining phyllo triangles. Serve hot.