01 - Preheat oven to 425°F. Line a large sheet pan with parchment paper or foil for easy cleanup.
02 - In a small bowl, whisk together olive oil, lemon juice, garlic, Dijon mustard, honey, oregano, salt, and pepper until well combined.
03 - Place asparagus and cherry tomatoes on the prepared sheet pan. Drizzle with half of the marinade and toss to coat evenly. Spread vegetables across the pan, leaving space for salmon fillets.
04 - Nestle salmon fillets among the vegetables. Brush the tops with remaining marinade and season with additional salt and pepper to taste.
05 - Scatter thinly sliced red onion pieces over the vegetables and around the salmon.
06 - Roast in preheated oven for 15 to 18 minutes, or until salmon flakes easily with a fork and vegetables are tender-crisp.
07 - Remove from oven. Garnish with chopped fresh parsley and serve immediately with lemon wedges on the side.