Prep ingredients: Trim tomatoes and cucumber and cut into 1⁄2-inch pieces. Trim shallot, then halve, peel, and thinly slice. Roughly chop parsley leaves and tender stems.
Drain and rinse chickpeas. Pat very dry with a paper towel.
Make salad: In a medium bowl, whisk vinegar, 3 tablespoons oil, and a pinch each salt and pepper. Add cucumber, tomato, and half of the shallot (save rest for step 3). Stir and set aside to marinate.
Make couscous: Heat 1 tablespoon oil in a small saucepan over medium-high. Add remaining shallot and cook until lightly browned, about 2 minutes. Add couscous and stir to coat. Add 2⁄3 cup water and 1⁄4 teaspoon salt. Cover, remove from heat, and let sit until grains are tender and water is absorbed, 5–7 minutes.
Cook chickpeas: Heat 1 tablespoon oil in a medium skillet over medium-high until shimmering; add chickpeas and 1⁄2 teaspoon salt and cook, stirring occasionally, until chickpeas are browned and slightly crisp, about 5 minutes. Add ras el hanout, and cook 30 seconds. Add 1⁄4 cup water and cook until sauce is nearly reduced, about 30 seconds.
Make yogurt: Stir 1 tablespoon oil, 1⁄4 teaspoon salt, and a few generous grinds pepper into yogurt container (no need to dirty a bowl).
Finish & serve: Fluff couscous with a fork, then add chickpeas to saucepan and stir. Season to taste with salt and pepper. Add parsley to salad and season to taste with salt and pepper. Spoon yogurt onto plates. Divide couscous between plates and top with salad and any leftover dressing. Drizzle with oil.