Combine all the ingredients for the dough in a large mixing bowl or the bowl of a stand mixer. Mix and knead until a smooth dough forms, about 6~8 minutes on the machine and 10~12 minutes by hand.
Transfer the dough to a lightly greased bowl, cover with plastic wrap and set aside for about 1 hour or until doubled in volume.
Turn the dough out onto a lightly floured work surface. Divide the dough in half. Gently form each piece into a rectangle and form into a log. Loosely cover the logs with plastic wrap and let rest at room temperature for 30 minutes.
In the mean time, combine the all purpose, sugar and ½tsp canola oil and water in a small saucepan. Cook the flour paste over medium heat, whisking, until bubbles start to form around the edges and the mixture becomes thick and opaque, about 2 minutes. Set aside to cool.
Put a pizza stone on the lowest rack of the oven and preheat the oven to 450°F. Let the stone heat for at least 30 minutes.
Place one of the dough log on a parchment and stretch/ roll it out into 14"x5" rectangle. Using the fingers, press 5 deep lengthwise ridges into the dough, making sure not to break the dough.
Rub half of the flour paste over the surface and sprinkle with half of the nigella and sesame seeds.
Slide the dough with the parchment onto the pizza stone and bake until the bread has puffed up and is golden brown, about 18 minutes. Transfer the loaf to a wire rack. Repeat with the remaining dough. Serve warm. Store any leftovers in an airtight ziploc bag at room temperature for up to 2 days.