Fresh ginger is used in the poaching liquid for the chicken, as well as used to flavor the cucumber salad in this quick weeknight dinner.
Season chicken with salt, pepper, and zest. Heat 3 tablespoons oil in a large straight-sided skillet on high; add chicken and cook 4 minutes. Flip; add garlic, 1 teaspoon ginger, beans, and 1/3 cup water. Season with salt and pepper. Cover and simmer until chicken is just cooked through, 6 to 8 minutes. Coarsely chop cilantro.
Bring 1 cup water to a boil in a small saucepan. Add a pinch of salt and couscous; remove from heat, cover, and let stand 5 minutes. Cut cucumbers into 1/2-inch pieces and tomatoes into 1/2-inch wedges. Toss both with 1/4 cup cilantro and remaining 1 teaspoon ginger and 3 tablespoons oil; season with salt and pepper. Fluff couscous with a fork; stir in remaining 1/4 cup cilantro. Slice chicken; serve, with beans, cucumber salad, couscous, and lemon.