1. Toss together first 6 ingredients in a medium bowl. Slice fennel bulb thinly, reserving fronds. Finely chop fennel fronds to equal 1 1/2 Tbsp., and sprinkle over salad. Add fennel slices to salad.
2. Toss together apple slices, vinegar, and sugar in a small bowl. Add apple mixture to fennel mixture; toss to combine.