Preheat the oven to 400°F (200°C).
Make the dill yogurt sauce by mixing together all the ingredients and set aside.
On a large non-stick sheet pan toss quartered potatoes with 2 tbsp olive oil, 1 tsp salt, pinch pepper and 1 tsp garlic powder and spread out on the pan. Bake for 20 minutes. *If you don't have a non stick sheet pan, be sure to line the pan with a piece of parchment paper*
After 20 minutes, remove the pan from the oven and push the potatoes to one side of the pan.
Add the asparagus to the sheet pan and toss with 1 tbsp olive oil, 1 tsp salt and a pinch of pepper. Move the asparagus to the other side of the sheet pan.
Add the salmon filets to the middle of the sheet pan, skin side down. Drizzle the salmon with 1 1/2 tbsp olive oil, spreading between the filets. Sprinkle the salt, pepper and garlic powder seasonings evenly over the salmon filets. Top each filet with a slice of lemon.
Place the baking sheet back into the oven for 12-15 minutes or until the salmon flakes easily with a fork and is no longer opaque inside. The potatoes should be tender and the asparagus crisp-tender.
Serve the salmon, potatoes and asparagus with more lemon slices, dill sauce and salt and pepper if desired.