Total Time : 2 hr 10 min
Prep : 30 min
Inactive : 10 min
Cook : 1 hr 30 min
1/2 medium red onion, roughly chopped
1/2 cup roughly chopped fresh parsley
1/2 cup roughly chopped fresh cilantro
1/4 cup roughly chopped fresh tarragon
1/4 cup roughly chopped fresh dill
1/4 cup chopped walnuts
3 cloves garlic
1/4 cup extra-virgin olive oil
1 tablespoon red wine vinegar
Kosher salt and freshly ground pepper
1 cup plain yogurt
1 6- to 7-pound roasting chicken
2 pounds plum tomatoes, halved lengthwise
Preheat the oven to 450 degrees. Pulse the onion, parsley, cilantro, tarragon, 2 tablespoons dill, the walnuts and garlic in a food processor. Add 3 tablespoons olive oil, the vinegar, 2 teaspoons salt, and pepper to taste; pulse until smooth.
Stir half of the herb paste with the yogurt in a small bowl; cover and refrigerate.
Season the chicken inside and out with salt and pepper. Loosen the skin with your fingers; rub some of the remaining herb paste under the skin and the rest on the outside of the bird. Truss the chicken. Place in a roasting pan; roast until the skin turns golden, about 30 minutes.
Reduce the oven temperature to 375 degrees. Toss the tomatoes with the remaining 1 tablespoon olive oil in a bowl; season with salt and pepper. Baste the chicken with the drippings and add the tomatoes, cut-side down, to the pan. Continue roasting until a thermometer inserted in the thickest part of the thigh registers 155 degrees, about 1 hour. Season with salt and pepper; let the chicken rest 10 minutes before carving.
Arrange the chicken and tomatoes on a platter; sprinkle with the remaining 2 tablespoons dill. Serve with the yogurt sauce.