1large Lebanese cucumber200 gmsashimi-grade yellowfin tunaTo serve:Avruga caviar (see note)To serve:caramelised red wine or caramelised balsamic vinegar (see note)
Slice cucumber lengthways to 3mm-4mm thick (avoiding seeds), then cut each piece widthways into 6cm-long rectangles.
Thinly slice tuna across the grain to 3mm thick, then trim into rectangles the same size as cucumber (reserve scraps and use for tuna tartare or toss raw through pasta, if you like).
Scatter cucumber with a little salt, top each piece with a slice of tuna and a spoonful of Avruga. Drizzle with a little vinegar and serve.
Note Avruga caviar, the roe of wild herring, is available from fishmongers and select delicatessens. Caramelised red wine vinegar and caramelised balsamic vinegar are available from select delicatessens.