In a saucepan, combine the rice vinegar, fish sauce, and caster sugar. Over a low heat, stir the sauce until the sugar is disolved. Taste for seasoning, and adjust as needed. The extra salt is only necessary if the sauce is too bland; alternatively, extra fisha sauce can be used.
For a bit of a kick, a few slivers of red chillies can be added to the sauce at this point.
Top and tail the carrot, and peel. Using a madoline with a julienne blade, cut the carrot into thin shreds. Barring a madoline or a spiralizer, use a vegetable peeler to make thin ribbons of carrots.
Leave the carrots to marinate in the sauce.
Top and tail the cucumber, and slice into 3mm rounds.
Remove the tail from the red chillie, cut in half lengthwise. Depending on the level of heat desired, scrape out the spongy rib and seeds or leave in, before cutting into slivers.
Pick the leaves from the coriander stalks, finely chop the stalks. Add the chopped stalks to the pickling carrot.
Just before assembling the banh mi, toss the cucumber and chillies into the pickling liquor.
Heat a frying pan or griddle pan until smoking.
Season the beef with salt and pepper, and drizzle with the sunflower oil.
When the pan is hot, sear the beef on all sides, and cook until about medium, remove from the pan, and leave to rest.
Banh mi are ideally made with soft or day old baguettes, but can be made with fresh if preferred. Split the baguette in half, and top with the pickled vegetables, drizzling with some of the pickling liquor.
Slice the beef thinly, stack onto the bread, and finish with the coriander leaves. Cut the baguette into three, and serve immediately.
«Try varying the pickled veg by using daikon or normal radishes. For non-beef alternatives, try some prawns or mushrooms instead.»