• Take the steak out of the freezer 10 minutes before slicing.
• Preheat the barbecue to medium-high.
• Using a chef’s knife, finely shave the par-frozen meat. Place in a shallow bowl. Add the oil, garlic and lemongrass and season generously with salt and pepper. Stir to coat. Cover and allow to marinate for 5 minutes.
• Meanwhile, to make the sauce, combine all ingredients in a bowl. Set aside.
• Working in batches, quickly sear the meat on the hot barbecue plate for about 30 seconds each side. Remove and add to the sauce mixture.
• To make pickled veg, combine all the vegetables in a large bowl. Add the vinegar and sugar and toss to coat.
• To serve, split the rolls down the middle and spread one side with pate and other side with mayonnaise.
• Remove the beef from the sauce, allowing excess to drip off, and add to the rolls. Top with the pickled vegetables and herbs. Scatter with chilli, if using and sesame seeds. Serve and eat immediately.

TIP: If you prefer, replace bread rolls with cooked vermicelli noodles and omit pate for a Vietnamese Noodle Salad.