To make the dressing, simply measure the ingredients into a tightly-lidded jar with a good pinch of salt and freshly ground black pepper. Shake vigorously, until blended.
Toast the pecan nuts in a dry frying pan set over a medium heat, shaking the pan until they turn a shade darker. Cool and roughly chop.
Divide the sliced pears and rocket leaves between four serving plates. Scatter with Parmigiano Reggiano shavings and drizzle the dressing over. Scatter with the pecans to finish.