Ingredients:

Yogurt Sauce

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

Salmon

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
Kosher salt
8 ounces small cherry tomatoes on the vine (optional)

Tomatoes and Couscous

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

Preparation:

Yogurt Sauce
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.

Salmon

Preheat oven to 325°. Remove pin bones from salmon. Pour 4 Tbsp. 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 Tbsp. 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.

Tomatoes and Couscous

Toss tomatoes with 3 Tbsp. 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 Tbsp. 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.