Preheat the oven to 400 degrees F (200 degrees C).
Zest Lemon (1/2) into a small bowl. Juice into a second small bowl and remove the seeds with a fork. Set aside.
Cut one inch off the end of the Asparagus (12 ounce) spears and discard the ends, then set aside.
In a third small bowl, combine the Dijon Mustard (2 tablespoon), Tamari Soy Sauce (2 teaspoon), and lemon juice and stir until well incorporated.
Pat dry the Salmon Fillet (2) with paper towels and cut in half. Place the salmon in a plastic bag and pour in the marinade. Massage the fish gently so that the fillets are evenly coated. Place in the refrigerator for ten minutes.
Place the asparagus in a single layer on half of a sheet pan, leaving room for the salmon. Drizzle the asparagus with Olive Oil (1 teaspoon), Salt (1/4 teaspoon) and Ground Black Pepper (1/4 teaspoon). Hold for next step.
Remove the salmon from the marinade and place on the sheet pan next to the asparagus. You'll have some marinade remaining in the bag. Spoon it over the salmon fillets. Roast in the oven for nine minutes.
Divide the asparagus into two portions and place in the center of two plates. Stack the salmon fillets at an angle on top of the asparagus. Garnish the fish with lemon zest.