Cabbage Salad with Toasted Coriander and Cumin Mayonnaise

I made the mayonnaise from scratch for this recipe and added extra vinegar as was recommended but it never developed the tang I was looking for. Amanda Hesser suggested a little sour cream to 'sharpen up the flavors' but I didn't have any....that might have made the difference. I did use all savoy cabbage instead of the savoy/red cabbage mix called for and I minced the green parts of a couple green onions in place of the chives (try not to shop the produce dept on Sunday night...you will be disappointed at what they don't have in stock). Between three of us, we ate the entire five cups of salad in a sitting so it was pretty good but everyone agreed they've had better slaw so, for the trouble, it isn't something I'll make again.