Preheat the oven to 400°F.
Rinse quinoa with clean water in a sieve and add it to a medium pot with the vegetable broth. Bring to a boil, then reduce heat to low and cover. Cook for 15 minutes, then remove from heat and let sit, covered, for an additional 10 minutes.
Removing salmon skin if necessary and pat it dry with a paper towel. Then, slice it into bite-sized cubes, about 1 cubic inch in size and add the cubes to a small bowl.
In a small bowl or jar, mix together Dijon mustard, lemon juice, and honey to make a thick sauce. Pour ¼ cup of the sauce over the cubed salmon and set it aside to marinade. Save the rest of the sauce for later.
Peel and slice the onion and break the "woody" ends off the asparagus. Add the onion and asparagus to a large baking sheet with the olive oil, salt, and pepper. Toss to coat evenly.
Roast the onions and asparagus on the top rack of the oven for 10 minutes, then remove the baking sheet and add the salmon (and sauce that the salmon is marinading in). Make sure everything is spread out in a single layer.
Roast for another 7-8 minutes until the internal temperature of the salmon reaches 125°F.
Assemble your salmon quinoa bowl by serving up the quinoa first, adding the fresh greens, and then the roasted asparagus, onion, and salmon. Finish with the extra sauce and enjoy hot.