Tamarind Mackerel Roll

Method

1. Open the mackerel, tip the whole tin into a sieve set over a bowl and walk away for four minutes. Tinned fish holds far more liquid than the drained weight suggests, and a wet filling will soak through the wrapper before you have finished rolling it.
2. Grate the ginger to a wet pulp, ring the green chilli, chop the tomato small, and cut the cucumber into batons about the length of your thumb. Pick the coriander into sprigs and keep it apart from the rest.
3. Warm the oil in a small pan and give the ginger and chilli one minute, then the Kashmiri chilli and the chopped tomato for four, pressing the tomato against the base as it slumps. Let the tamarind down with a spoonful of warm water, pour it in and cook it two minutes more, until the masala comes away from the pan in one piece behind the spoon.
4. Break the drained fillets into big flakes straight into the pan, soft bones and all, drop the flame to its lowest and turn them over in the masala for four minutes, lifting from underneath rather than stirring, until the flakes are hot the whole way through.
5. While the mackerel warms through, lay the low-carb tortilla over a second low burner for two minutes, turning it once, until it drapes over your hand instead of standing up on its own.
6. Lay the cucumber batons down the centre of the warm tortilla, spoon the tamarind mackerel along them, shower the coriander sprigs over the top and roll it away from you with one end tucked under.
7. Cut it once on the slant and start eating immediately, while the sour heat still has cold cucumber to work against.