Preheat the oven to 400 degrees. Line a rimmed baking sheet with foil and put in in the oven to heat up while you prepare the ingredients.
Melt the Cafe de Paris butter. (Or make the seasoned butter from Note 1.) Toss the rice, melted butter, scallions, capers and 2 tsps salt in a large bowl. Combine the olive oil and lemon juice and stir half the lemon mixture into the rice.
Remove the hot baking sheet from the oven and spread the rice mixture evenly around it. Bake on the lower rack about 12-15 minutes until edges of rice are crispy and brown.
While rice is baking, combine the mustard, brown sugar and remaining lemon juice mixture. Sprinkle salmon filet with pepper and ¾ teaspoon salt.
Toss the asparagus or broccoli with a drizzle of olive oil and the remaining ¼ teaspoon salt.
Remove rice from the oven and center the salmon over the rice. Distribute the asparagus evenly around the salmon. Spread the mustard mixture evenly over the salmon filet.
Return the baking sheet to the oven and bake another 10-12 minutes until the salmon is cooked through.
Remove the sheet pan from the oven and sprinkle fresh herbs evenly over the salmon, vegetables and rice. Drizzle with olive oil if desired.
Serve immediately.