Finely chop the onion and chilli, then scatter these into a small bowl.
Mix the vinegar, maple syrup and soy sauce in a small bowl and pour this over the onion & chilli. Set aside.
Chop the tofu into 2cm cubes.
Heat a spoonful of oil in a wok, add the chilli flakes and cook on all sides until golden. Transfer them to a plate lined with kitchen paper.
Dice the beetroot into similar size chunks as the tofu.
Scatter the tofu and beetroot onto a serving plate. Pour the marinated onion & chilli all over (including the marinade).
Sprinkle some coriander leaves on top and serve.