Fennel and Cabbage Slaw

1 fennel bulb, core removed, cut into quarters, and sliced very thinly, fronds reserved

1 cup thinly sliced purple cabbage

2 scallions, chopped

2 strips bacon, cooked crisp and chopped

For the dressing:

1/4 cup mayonnaise

3 tablespoons red wine vinegar

3 tablespoons chopped fennel fronds

1 teaspoon sugar

Salt and freshly ground black pepper