Step 1

Heat oven to 425°F. With mortar and pestle, coarsely crush coriander and cumin seeds. Stir in red pepper flakes, 1/4 teaspoon sumac, and a pinch of salt.

Step 2

On rimmed baking sheet, toss tomatoes and garlic with 1 tablespoon oil and spices. Roast 12 minutes.

Step 3

Meanwhile, heat 1 teaspoon oil in small skillet on medium. Season chicken with 1/4 teaspoon each salt and pepper and cook until golden brown, 5 to 6 minutes. Turn and cook 1 minute.

Step 4

Toss tomato mixture with chickpeas, nestle chicken among tomatoes, and continue roasting until chicken is cooked through, 6 to 8 minutes more. Transfer chicken to cutting board and let rest 5 minutes before slicing.

Step 5

In bowl, toss farro, scallion, vinegar, remaining 1 tablespoon oil, and a pinch each of salt and pepper. Fold in chickpea-tomato mixture and chicken, then greens.