Preheat oven to 400 degrees F. Spray a baking sheet with cooking spray or cover with parchment paper. Blanch asparagus spears in boiling water for 3 minutes; drain and submerge in ice water to stop the cooking. Drain, then pat dry and cut into 1/4-inch pieces; place in a medium glass bowl. Mix in eggs, red onion, 2 Tbsp. dill, 1/2 the cream cheese (62 g), mayonnaise, mustard, salt and pepper. Set aside. Cut pastry into 4 equal pieces; place 1 salmon fillet on the centre of each pastry piece. Season with salt and pepper. Top with egg mixture.
Fold sides of pastry over salmon and press pastry together to seal the seam. Brush with egg wash. Place on prepared baking sheet. Bake for 15 minutes. Reduce oven temperature to 325 degrees F and bake for 15 minute more or until pastry is flaky and golden brown. Let stand 5 minutes before serving.
Meanwhile, bring broth, lemon zest, lemon juice and remaining dill to a simmering boil. Add remaining cream cheese and cook until melted, stirring constantly with whisk. Cook 10 minutes or until thickened, stirring occasionally. Remove from heat until ready to serve. Serve salmon bundles topped with sauce.