Heat oven to 450˚F. Zest lemon until you have 1 teaspoon of zest. Combine pistachios, parsley and lemon zest in bowl, and set aside until ready to serve. Cut zested lemon into 4 wedges, for serving.
Toss broccoli rabe in bowl with 2 tablespoons oil, teaspoon salt and teaspoon pepper. Arrange on half of rimmed baking sheet. Rub salmon with remaining oil, and sprinkle with teaspoon salt and teaspoon pepper. Arrange salmon on other half of baking sheet.
Roast until broccoli rabe is tender and centers of salmon are still translucent when checked with the tip of a paring knife (it should register 125˚F on a meat thermometer for medium-rare), approximately 8–12 minutes. Divide among plates, sprinkle salmon with gremolata, and serve immediately with lemon wedges. Serves 4.