Preheat oven to 425 degrees. Line a large baking sheet with parchment, or spray with oil.
Toss the Brussels sprouts with 1 tablespoon olive oil, salt, and pepper. Spread onto one side of the baking sheet.
Mix the dried parsley, 1 tsp each garlic and onion powder, dill, and a pinch of salt and pepper. Drizzle the potatoes with 1 tablespoon olive oil and toss with the ranch seasoning. Spread onto the other side of the sheet. Roast for 15 minutes.
Combine the brown sugar, smoked paprika, chipotle chili powder, the remaining 1 tsp garlic and onion powders, and a pinch of salt and pepper. Rub the salmon filets with the spice mixture. Drizzle with 2 tablespoons olive oil.
Arrange the salmon filets around the veggies. Place a pat of butter onto each filet. Roast for 10-15 minutes, or until desired doneness. If you didn't use parchment on your pan, switch the broiler to high in the last 1-2 minutes for a crispy finish.
To make the dressing, stir together the yogurt, tahini, honey, dijon, lemon juice, garlic cloves, and a pinch of salt and pepper. Divide the hot salmon, potatoes, and sprouts among plates and drizzle with the tahini sauce.