Lightly fry shallots in the olive oil over a low heat until golden (approx 8 minutes). Set aside.
Sashimi Plate
Put the fish pieces in the freezer for 10 minutes, or until quite firm. Be careful to make sure it does not freeze.
Using a very sharp knife, slice the fish into 3mm (0.1 inch) thick slices and lay on a chilled platter, in an overlapping pattern. Scatter the coriander leaves over the top, then sprinkle with the diced tomato and red onion. Season with sea salt and ground white pepper.
Heat the oil in a frying pan over a medium-high heat and fry the potato for 6 minutes, or until golden and just cooked. Sprinkle over the fish. Squeeze over lime and then drizzle over the soy sauce. Scatter the chili and chives on top.
Reheat the shallot oil over a medium-high heat until it is sizzling and drizzle over the fish, to serve