Cut out the core of the cabbage. Remove and discard the outer leaves. Slice the remaining cabbage as finely as you can but don't stress too much. If I have my food processor out I use that but mostly it's quicker with my knife.

Place cabbage in a large bowl. Combine mayonnaise and lemon juice in a small bowl or jar with a pinch of salt. Toss the dressing on the cabbage. Allow to sit for 5-10 minutes (or up to an hour) so the cabbage softens slightly.

When you're ready to serve, pick the leaves from the parsley (or finely chop the whole bunch if you're short on time). Toss the parsley in with the cabbage. Chop walnuts and sprinkle them over along with the parmesan.