Preheat oven to 425 degrees F.

Cut a piece of parchment paper to fit on a cookie sheet, and then lay it on the sheet. Wash

the unpeeled sweet potatoes and onions and slice ?" thick. Put sweet potatoes and onions

on the parchment paper in a single layer. Drizzle with olive oil and salt. Bake for 15

minutes.

Meanwhile, mix garlic, dry mustard, lemon juice, and rosemary to make a paste, and set

aside.

Remove sweet potatoes and onions from oven (keep on the cookie sheet). Place the

asparagus on the paper next to the sweet potatoes and onions. Sprinkle the lemon zest and

on the asparagus. Lay salmon on top of the asparagus and onions. Spread mustard paste

on top of salmon.

Return sheet to oven and roast for 12 minutes. Salmon is done when flesh flakes with

gentle pressure.