Raw scallops are one of my favourite shellfish to use for sashimi; in fact, when they are fresh straight out of the sea, it almost seems a shame to cook them. Try to buy them live in the shell and get your fishmonger to cut and clean them for you. (I wouldn't use the roe for this dish but if you save them and slice them and toss into some pasta with butter, chilli and olive oil they can be really delicious.)
4 large scallops, cleaned
2 medium carrots, trimmed, peeled and cut into neat 3cm batons
a cucumber, cut into neat 3cm batons without the seeds in the centre
1 medium green chilli, very thinly sliced with the seeds
120-150ml rice wine vinegar
Put the carrots into a non-reactive container or bowl with the sliced chilli and cover with the rice vinegar and leave in the fridge overnight. Mix in the cucumber and leave for 20 minutes.
To serve, cut each scallop into three or four slices, arrange the carrots and cucumber on serving dishes, lay the scallops neatly on top and spoon over a little of the vinegar.