While there are a variety of za’atar spice blends, the majority of them include oregano, thyme, sumac and sesame seeds, making it a great short cut ingredient that imparts a lot of flavor. Za’atar, lemon zest and pistachio are mixed with panko to coat the halibut, giving this mild fish plenty of delicious fresh flavor with a crunch.
Place a rimmed baking sheet in the center of the oven and preheat to 450˚ F. Grate the lemon zest and set aside. Cut the lemon into 4 wedges and add to a large bowl along with the broccolini, 2 tablespoons olive oil, 1/2 teaspoon salt and the red pepper flakes. Toss to coat. Spread on the hot baking sheet and roast until crisp-tender and charred, flipping halfway through, 15 to 20 minutes.
Meanwhile, pulse the pistachios in a food processor until finely chopped. Add the reserved lemon zest, panko, za’atar and 1/2 teaspoon salt; pulse to combine. Transfer to a shallow bowl. Press the halibut fillets in the pistachio mixture, turning to fully coat all sides.
Heat the remaining 3 tablespoons olive oil in a large nonstick skillet over medium heat until hot. Add the halibut and cook, turning once, until golden brown, about 4 minutes per side.
Season the halibut with salt and divide among plates. Serve with the roasted broccolini and lemon wedges.