Preheat the oven to 400 degrees Fahrenheit/200 degrees Celsius.
Toss potatoes, carrots, and shallots with olive oil, paprika, salt, and black pepper. Spread evenly on a large sheet pan. Bake for 30 minutes. Flip vegetables and bake for another 10 minutes until potatoes are fork-tender.
Meanwhile, toss salmon cubes with olive oil, paprika, black pepper, garlic powder, salt, Dijon mustard, and honey. Let marinate while vegetables bake.
After 40 minutes, remove vegetables from the oven. Place salmon cubes on top and sprinkle with parsley. Return to the oven and bake for 10 to 12 minutes. Broil for 2 minutes if desired to finish.
Whisk together mayonnaise, Dijon mustard, honey, apple cider vinegar, paprika, salt, and black pepper until smooth. Drizzle sauce over salmon and vegetables before serving. Finish with a squeeze of lemon if desired.