Preheat oven to 350 degrees F.
Spread the pistachios on a baking sheet. Bake at 350 for 4-7 minutes, or until toasted and fragrant. Keep an eye on them so they don't burn. Remove from the oven and immediately remove to a plate or bowl, and set aside.
MEANWHILE, prepare the asparagus - wash all the spears, and snap the woody ends off. (no need to use a knife for this, and it's a great activity to keep little hands busy if you have kids who want to "help")
Turn the oven up to 400 degrees F.
Spread the asparagus in a single layer over 1 large baking sheet. (if they are crowded, they will steam instead of roasting)
Drizzle the asparagus with 1-2 tsp oil and use your hands to make sure the spears are coated.
Roast in the oven for 8-10 minutes, depending on the thickness of your asparagus.
While the asparagus is cooking, in a small bowl whisk together the lemon juice, garlic, basil, salt, and pepper. Whisking constantly, drizzle in the remaining 2 Tbsp oil.
Chop the cooled pistachios, if desired.
Plate the asparagus, drizzle with the dressing, and sprinkle with the pistachios. Serve immediately while it is warm from the oven.