Heat 1 tbsp oil and fry onion on a low heat until softened. Add sugar and allow to caramelise for 5 minutes. In a second pan, heat remaining oil on high and flash fry beef slices until just cooked. Open out sub roll and fill with provolone cheese, ribeye and caramelised onions, then flash under the salamander to heat through. Top with cucumber and serve with extra SAFRIES fries.