Ingredients

• 1 cup plain Greek yogurt
• 1/2 cup plain yogurt
• 3 tablespoons chopped fresh dill
• 2 tablespoons chopped fresh chives
• 1 tablespoon finely grated lemon zest
• Kosher salt
• 6 tablespoons olive oil, divided
• 1/2 bunch dill fronds
• 1/2 bunch thyme sprigs
• 1 3-pound piece center-cut skin-on salmon fillet, preferably wild king, pin bones removed
• Kosher salt
• 8 ounces small cherry tomatoes on the vine (optional)
• 2 cups cherry tomatoes, halved
• 4 tablespoons olive oil, divided
• 2 tablespoons chopped flat-leaf parsley
• 2 tablespoons za'atar (optional)
• Kosher salt
• 2 cups Israeli couscous
• 1 tablespoon unsalted butter
• Ingredient info: Za'atar, a Middle Eastern spice blend that includes sumac, herbs, and sesame seeds, is available at specialty foods stores, Middle Eastern markets, and igourmet.com.

Instructions

1. Mix first 5 ingredients in a medium bowl until well combined. Season with salt. DO AHEAD: Can be made 3 days ahead. Cover and chill.
2. For salmon: Preheat oven to 325°F. Pour 4 tablespoons oil in a roasting pan just large enough to fit the salmon. Make a bed of herbs in bottom of pan; top with salmon, skin side down. Drizzle salmon with remaining 2 tablespoons oil and season with salt. Top with tomatoes, if using. Bake until salmon is just cooked through in the center (a small knife will slide easily through flesh), 25-30 minutes.
3. Preheat oven to 325°F. Pour 4 tablespoons oil in a roasting pan just large enough to fit the salmon. Make a bed of herbs in bottom of pan; top with salmon, skin side down. Drizzle salmon with remaining 2 tablespoons oil and season with salt. Top with tomatoes, if using. Bake until salmon is just cooked through in the center (a small knife will slide easily through flesh), 25-30 minutes.
4. For tomatoes and couscous: Toss tomatoes with 3 tablespoons oil, parsley, and za'atar, if using, in a medium bowl. Season to taste with salt. Set aside. Bring a medium pot of lightly salted water to a boil. Add couscous and cook until tender, about 7 minutes. Drain couscous; transfer to a large bowl. Stir in butter and remaining 1 tablespoon oil. Season to taste with salt. Gently fold tomatoes into couscous. Use a large spoon or fork to serve salmon, leaving skin in pan. Serve with yogurt sauce and couscous.
5. Toss tomatoes with 3 tablespoons oil, parsley, and za'atar, if using, in a medium bowl. Season to taste with salt. Set aside.
6. Bring a medium pot of lightly salted water to a boil. Add couscous and cook until tender, about 7 minutes. Drain couscous; transfer to a large bowl. Stir in butter and remaining 1 tablespoon oil. Season to taste with salt. Gently fold tomatoes into couscous.
7. Use a large spoon or fork to serve salmon, leaving skin in pan. Serve with yogurt sauce and couscous.