Preheat oven to 325˚. In a bowl, toss together pistachios, sesame seeds,honey until almonds are well coated. Spread out into a single layer on a parchment covered sheet tray. Roast for 14 to 16 minutes until sesame seeds are starting to brown. Remove and set aside, letting cool completely.
While the pistachios are roasting, supreme the grapefruit (see note) and place in a bowl along with the arugula, fennel, and goat cheese. One nuts are done and slightly cool, add roughly half to the salad.
Whisk together the dressing ingredients in a small bowl, pour over salad, and toss until the salad is mixed and well coated with dressing. Serve with the extra pistachios.