Gather your ingredients. Make sure to use Meyer lemons, otherwise it will turn out too tart.
Preheat the oven to 375 degrees.
Spread pistachios on a baking sheet, and stick in the oven. Toast until fragrant, about 8 minutes.
When done toasting, transfer the pistachios to a plate to cool.
While the pistachios are cooling, cook the whole wheat spaghetti.
Cut the lemon into wedges, removing an seeds and pith from the middle.
Chop the shallot into 6 or 8 chunks.
When the pasta is done, drain into a colander. Make sure to reserve some of the cooking water.
Combine the oil, pistachios, shallots and lemons (yes the entire wedges, peel and all!) in a Vitamix and blend. If necessary, use some of the reserved cooking water to thin it out.
Return the pasta to the pot, and add the arugula, and a splash of the cooking liquid. The cooking liquid helps the arugula wilt a bit.
Add the pistachio mixture and stir well.
Season with freshly ground black pepper.
Season with sea salt.
Serve immediately. Sometimes I toss some beans into this dish to add a bit of protein. It taste delicious with borlotti beans! Recipe adapted from Martha Stewart.