Lightly oil 2 large baking trays. Pat dough out on a lightly floured surface to make a 30 x 15 cm rectangle. Cut evenly into 12 bread sticks, each 15 cm long. Gently twist each stick. Place on baking trays. Cover loosely with plastic wrap. Leave to rise in a warm place until doubled in volume, about 1 hour.
Heat oil in a large non-stick frying pan over medium heat. Add onion. Sauté until very soft and golden, about 12 minutes.
Preheat oven to 200°C. Place an oven rack in the lowest position and one in the highest position.
Just before baking, distribute sautéed onions over surface of each bread stick, taking care not to deflate dough. Sprinkle each stick with the salt.
Bake on the low rack for 15 minutes. Then move to the top rack. Bake until the onion is crisp and golden, 5 to 8 minutes. Transfer to a wire rack to cool.