Coarsely grate or slice (thinly) the cabbage (without using the tough middle bit of the cabbage which can be chopped up and added to soup). Combine the pickling ingredients and pour over the cabbage stirring thoroughly. Cover and leave in the fridge overnight.
To make the slaw combine the cabbage with the pears, cilantro, red onion, walnuts, season to taste and drizzle with oil and lemon juice. Scatter the lemon zest over the top and serve.