Slice fennel bulb into very thin strips. Chop fennel fronds and arugula. Set aside. In a small bowl, whisk together 2 tablespoons reserved grapefruit juice, olive oil, vinegars, honey, salt and ...
and fennel fronds in a large bowl. Add dressing, and toss to coat. Season with salt and pepper. Garnish with crumbled goat cheese and serve immediately.