Preheat your oven to 450 degrees F. Lightly oil a sided baking sheet.

In a medium bowl, combine all the miso dressing ingredients to form a loose paste. Divide in half.

With a paper towel, pat the tuna dry.

On a small plate, mix the black and regular sesame seeds as well as the dehydrated minced onion and roll the edges of each of the tuna steaks in the sesame seeds to coat.

Place the tuna steaks along one side of the baking sheet in a row and brush both sides of the tuna with half the miso dressing.

Place the sliced mushrooms in one corner of the baking sheet and the asparagus in the other corner.

Drizzle olive oil over both the mushrooms and asparagus and gently toss to coat.

Sprinkle the grated Parmesan over the asparagus and mushrooms.

Roast the tuna and vegetables for 7-10 minutes or until the internal temperature of the tuna has reached 125 degrees F.

While the tuna is roasting, toss the mixed greens with the other half of the miso dressing. If you find it a little too thick, you can add an additional 1 tsp of lemon juice and 1 Tbsp of olive oil.

To serve, place mixed greens in the center of each plate, place the tuna steak on top of the mixed greens.