Preheat oven to 425°F (220°C). Line a baking sheet with parchment.
Toss potato wedges and broccoli with 2 tbsp olive oil, salt, and pepper. Spread in an even layer and bake for 20 minutes.
Push potatoes to one side. Place salmon fillets on the sheet, drizzle with remaining olive oil, and season with salt and pepper.
Return to oven and bake another 12–15 minutes, until salmon is tender and potatoes golden.
Meanwhile, stir together yogurt, garlic, lemon zest & juice, dill, salt, and pepper for the sauce.
Serve salmon and potatoes hot with a generous spoonful of lemon-dill yogurt. Garnish with fresh dill.