Preheat oven to 425F and line baking sheet with parchment paper.
Optional but recommended: microwave whole baby potatoes for 2 minutes to pre-soften. This helps them cook to the perfect texture in the oven. then cut into quarters.
Place asparagus on baking sheet and drizzle 2 tbsp olive oil, 1/2 tsp salt, and 1/4 tsp pepper. Toss.
Place potatoes on baking sheet next to asparagus and drizzle 2 tbsp olive oil, 1/2 tsp salt, and 1/4 tsp pepper. Toss.
Bake in oven for 20 minutes. While baking, prepare salmon.
Whisk together 1 tbsp olive oil, grainy mustard, maple syrup, garlic, 1 tsp salt, 1/2 tsp pepper, and paprika.
Once vegetables have cooked, place salmon skin side down on baking sheet. Brush fillets with half of the sauce. Spoon remaining sauce on potatoes and asparagus, tossing to blend.
Bake for 12-14 minutes or until salmon is fully cooked (may depend on thickness of salmon).
Serve immediately.