Preheat your oven to 400°F and line a small baking sheet with parchment paper.
Trim the woody ends off the asparagus, place them on the baking sheet, and lightly mist with oil or toss with a tiny drop of the olive oil and a pinch of salt.
Roast the asparagus for 10-12 minutes until tender and slightly charred.
In a small bowl, whisk together the lemon juice, Dijon mustard, and half of the olive oil to create a dressing.
Toss the cooked lentils with the dressing and set aside to marinate.
Pat the salmon fillet completely dry with a paper towel and season with salt and pepper.
Heat the remaining olive oil in a non-stick skillet over medium-high heat.
Place the salmon skin-side down in the pan and press gently with a spatula for 30 seconds to ensure even contact.
Sear the salmon for 4-5 minutes on the skin side until crispy, then flip and cook for another 2-3 minutes until desired doneness is reached.
Plate the lentil salad alongside the roasted asparagus and top with the seared salmon.