Whisk the flour, salt and baking soda in a medium bowl. Combine the tahini, brown sugar, vanilla and melted butter in a large bowl and mix with a wooden spoon until smooth. Stir in the eggs until incorporated, then stir in the flour mixture until just combined. Stir in the chocolate chunks. Cover and refrigerate until firm, about 1 hour.
Position racks in the upper and lower thirds of the oven; preheat to 375 degrees F. Roll heaping tablespoonfuls of dough into balls and arrange about 3 inches apart on 2 ungreased baking sheets. Flatten slightly with your fingers. Bake, switching the pans halfway through, until the cookies are set and lightly browned around the edges, 14 to 16 minutes. Let cool 1 minute on the baking sheets, then transfer to racks to cool completely.