Preheat oven to 400°F. Stir together mustard, pepper, salt, paprika, and 1 tablespoon oil in a small bowl. Pat salmon dry using paper towels, and rub mustard mixture all over top and sides of salmon.

Heat 1/2 tablespoon oil in a large ovenproof skillet over medium-high until shimmering. Add salmon, skin sides down; cook, undisturbed, until skin begins to crisp and release easily from skillet, 3 to 4 minutes. Carefully flip salmon; cook until golden brown, 1 to 2 minutes (salmon will not be fully cooked through). Transfer salmon to a plate.

Reduce heat to medium, and add remaining 1 1/2 tablespoons oil to skillet. Add shallot; cook, stirring often, until softened, 2 to 3 minutes. Add garlic and crushed red pepper; cook, stirring constantly, until fragrant, about 30 seconds.

Stir orzo into skillet; cook, stirring constantly, until lightly toasted, about 2 minutes. Stir in broth; bring to a simmer over medium-high, stirring often. Reduce heat to medium-low; cover and cook until orzo is partially tender and broth is mostly absorbed, about 5 minutes, stirring once or twice.

Stir in asparagus, heavy cream, and lemon zest and juice. Bring to a simmer over medium; remove from heat. Arrange seared salmon fillets, skin sides down, over orzo mixture.

Transfer skillet to oven, and bake in preheated oven until salmon is just cooked through and flakes easily using a fork, asparagus is tender-crisp, and orzo is tender and creamy, 9 to 10 minutes.

Sprinkle dill and parsley over top. Serve immediately with lemon wedges for squeezing.