Step 1: Preheat your oven to 400°F (200°C). Line a large sheet pan with parchment paper for easy cleanup.
Step 2: In a large bowl, combine the trimmed asparagus, cherry tomatoes, and sliced red bell pepper. Drizzle with 1 tablespoon of olive oil and season with 1/2 teaspoon each of salt and pepper. Toss gently to combine.
Step 3: Place the vegetables on one side of the prepared sheet pan, spreading them into a single layer.
Step 4: Pat the salmon fillets dry with paper towels. In a small bowl, whisk together the remaining 1 tablespoon of olive oil, dried oregano, dried thyme, garlic powder, and the remaining 1/2 teaspoon each of salt and pepper.
Step 5: Place the salmon fillets on the other side of the sheet pan, leaving some space between them and the vegetables. Spoon or brush the herb-oil mixture evenly over each salmon fillet.
Step 6: Arrange a few thin lemon slices on top of each salmon fillet.
Step 7: Bake for 15-20 minutes, or until the salmon is cooked through and flakes easily with a fork. The cooking time will vary depending on the thickness of your salmon. The vegetables should be tender-crisp and slightly caramelized.
Step 8: Remove the sheet pan from the oven. Garnish with fresh chopped dill or parsley before serving immediately. Enjoy your delicious and healthy sheet pan salmon meal!