This recipe substitutes cucumber with fennel. Nigella claims that the usual cucumber causes this salad to become a soggy mess - the fennel was interesting; it was crisp although I can't say that I'm most fond of the taste, I still prefer cucumber.
The red onions were left to soak in the olive oil dressing for about 2 hours in the fridge. And Nigella is absolutely right, after about 2 hours, the red onion has lost it's sharpness and is much easier on the palate.
The three of us that were at dinner gobbled our way through the salad. I don't think any of us had a preference for Greek salad (again the olives) but the recipe itself seems to work wonders - once all the flavours are combined, you seem to just eat it all together. Anyway, adding this one to my tried and tested recipes; definitely one to make again.