Prepare Oven and Pan: Preheat your oven to 400°F (205°C) with the rack in the middle position. Line a large, rimmed baking sheet with parchment paper.

Mix Lemon-Herb Dressing: In a small bowl, vigorously whisk together the oil, fresh lemon juice, lemon zest, minced garlic, garlic powder, chopped fresh dill, the salt, and black pepper until emulsified. Measure out and reserve 1 ½ tablespoons of this dressing for the green vegetables later.

Marinate Salmon: Place the salmon fillets in a shallow dish. Pour about half of the remaining (unreserved) dressing over the salmon, coating the fillets evenly. Let them marinate in the refrigerator while you prep the vegetables.

Roast Sweet Potatoes: Place the sweet potato rounds on the baking sheet. Drizzle the last bit of the unreserved dressing over them and toss to coat. Arrange them in a single layer on one side of the pan. Bake for 12-14 minutes until they begin to soften.

Add Green Vegetables: Remove the pan from the oven. Push the sweet potatoes to the side to create room. Add the green beans, asparagus, and red onion. Drizzle the reserved 1 ½ tablespoons of dressing over these greens and toss lightly. Spread everything into an even layer.

Second Bake: Return the pan to the oven for 6-8 minutes, until the green vegetables are starting to become tender-crisp.

Add Salmon: Remove the pan again. Clear a space in the center among the vegetables. Place the salmon fillets skin-side down. Top each fillet with a lemon slice.

Final Bake: Bake for 12-18 minutes.

Note: Oven temperatures vary, so begin checking for doneness at the 12-minute mark to prevent overcooking. The salmon is done when it flakes easily with a fork and reaches an internal temperature of 135-140°F (57-60°C). The sweet potatoes should be tender and the greens vibrant.

Serve: Remove from the oven and serve immediately, ensuring each plate gets a portion of salmon and a mix of all vegetables.