Preheat Oven to 350 degrees Fahrenheit. Sift together salt, pepper and baking powder with the all purpose flour to aerate it.

Cut Chilled butter into cubes. Pulse the flour mixture with the butter in a food processor till it becomes crumbly.

Mix together the egg and the sour cream and then add it to the crumbly mixture in the food processor. Pulse a few times till it comes together and forms a soft dough.

Remove, divide into two parts, place in a greased bowl, cover with a damp tea towel and leave to rest for an hour.

Meanwhile empty the tuna can into a bowl. Drain and squeeze out the water as much as possible. Add salt, pepper and 1 tbs olive oil. Flake with a fork to mix everything well. Add the Harissa paste and drizzle the remaining 2 tbs olive oil, then flake again. Keep aside.

Take one part of the dough and roll into a ball, then on a pastry board dusted with flour flatten it with a rolling pin into a circle 12 inches in diameter.  Cut the circle into 8 equal triangles. Divide the filling into 16 portions, place one portion on each of the triangles at the base as in the picture above.

Take two corners of the triangle base and join them together as in the picture above. Then fold the base and roll it over while tucking the filling inside. Roll neatly again till the tip of the triangle like a croissant.

Glaze with egg wash, sprinkle black seeds on top then place them on a baking sheet lined with parchment paper and bake in the preheated oven for 30 - 35 minutes till golden.