Optional:
Press tofu for at least 10 minutes.
Add to a mixing bowl:
Slowly add ⅓ cup water, whisking as you go. The coating should be the consistency of pancake batter.
Add 1 tbsp mustard if using and mix.
Break the tofu into big crumbles and mix into the coating.
Heat oil in a non stick pan. Pour the tofu mix into the pan and spread so the tofu is on a single layer.
Cook on both sides until golden brown, adding oil as needed.
Modified from The Vedge