In a large bowl, stir together the flour, sesame seeds, salt, 1 Tbsp of the sesame oil, and the boiling water. The dough should just come together, but it will be far from smooth and instead quite shaggy and a bit dry. Although you might be tempted to add more water at this point, please resist, as the dough will come together beautifully once you knead it. If there are lots of crumbs and it’s not coming together at all, you can add a tiny splash more water, 1 or 2 Tbsp at most (variables like how you measure your flour and the humidity in the room can affect the dough, and it’s in these variables that the nuances of working with dough of all kinds live).