Preheat oven to 385° F.  Spray a sheet pan with cooking spray, or line it with foil.

In a mixing bowl, add the asparagus, cherry tomatoes, onions, garlic cloves, olive oil, and lemon juice and season with salt and pepper.  Mix well to make sure everything gets coated well.

Spread out the vegetable on sheet pan. Place it in the pan in the oven and bake for 10 minutes.

Sprinkle 1 Tablespoon of lemon juice on the salmon and season with salt and pepper.  Cut the salmon into 4 pieces.  Set aside and cover.

Take the pan out of the oven and push the vegetables to the sides to make room for the salmon in the middle.  Put the salmon pieces skinned side up on the tray and bake for another 5 minutes.

Remove the tray once more and turn the salmon pieces over. Cook for another 5 minutes and remove form the over to serve.

Remove all the cooked garlic cloves and 4 cherry tomatoes from the sheet pan and put in a blender or small processor.

Add the lemon juice, Dijon mustard, red wine vinegar, onion powder, salt and pepper.  Put the lid on and pulse a few times to roughly chop the ingredients.

Add in half of the olive oil and pulse 4 or 5 times.

Slowly drizzle in the remaining olive oil while running the blender.  Once all the oil has been added, continue to blend for another 10-15 seconds.