1Bring vegetable broth to a boil in a skillet. Stir in couscous, remove from heat, cover, and let sit for 5 minutes. Fluff with a fork and stir in minced garlic, capers, and olives. Set aside.
2While couscous cooks, preheat oven to 425°F. Spread pre-cut vegetables on a sheet pan, drizzle with 1.5 tbsp olive oil, season with half the salt and oregano, and roast for 8 minutes.
3Remove sheet pan from oven. Push vegetables to the sides, nestle salmon portions skin-side down in the center, and brush with remaining 1.5 tbsp olive oil. Season salmon with remaining salt, pepper, and oregano. Squeeze juice from half a lemon over everything.
4Return to oven and bake for 12–14 minutes, until salmon is opaque and flakes easily.
5Divide couscous among bowls. Top with roasted vegetables and a salmon portion. Garnish with fresh dill and serve with lemon wedges.