Preheat the oven to gas 7, 220°C, fan 200°C. Cook the chips and fish fingers to pack instructions.
Meanwhile, mix half the onion rings with the sugar and the juice from ½ lime. Set aside, stirring occasionally, until ready to serve.
In a large mixing bowl, mix the and oil. Season, then whisk together with a fork.
Use a julienne peeler or food processor attachment to cut the carrots into matchsticks, or coarsely grate. Tip into the dressing bowl with the cabbage and shredded coriander and toss together until everything is well coated. Season to taste with the remaining lime juice.
Split open the hot dog rolls. Halve the fish fingers and divide them between the rolls, sandwiching with a little slaw, the pickled onions and coriander leaves. Serve with the chips and more slaw on the side.