Use a vegetable peeler to peel the squash (or a knife if it’s a tough, thick-skinned variety). Then use the peeler to pare the squash flesh into ribbons. It’s easiest to cut it into manageable pieces, removing any seedy bits as you go, then pare each piece. The ribbons needn’t be long – in fact, short curls are easier to eat.
Put the squash ribbons into a large bowl, add a trickle of olive oil, season with some salt and pepper and toss together.
Put the chopped apple and about half the blackberries into a mortar or robust bowl. Use the pestle, or the end of a rolling pin, to bash up the fruit a bit – just enough to crush some of the apple and get the blackberry juices flowing. Add the lemon juice, 1 tablespoon olive oil, the sugar and some salt and pepper and mix well.
Arrange the raw squash over a large serving plate, or individual plates and spoon the juicy blackberry and apple mix on top. Scatter over the remaining whole blackberries and then the roughly bashed hazelnuts. Give the dish a final grinding of pepper, and serve.
Veg: Replace the squash with ribbons of raw carrot, beetroot or celeriac – they all work well.
Fruit: Try using autumn raspberries in place of the blackberries. And pear can certainly be used instead of apple.