Preheat your oven to 400°F (200°C) and line a small baking sheet with parchment paper.
Scrub the Russet potato thoroughly, pierce it several times with a fork, and rub the skin with 0.5 tsp of olive oil and a pinch of sea salt.
Place the potato directly on the oven rack and bake for 45 to 50 minutes until the skin is crisp and the center is tender.
While the potato finishes, pat the salmon fillet dry with a paper towel and place it on the prepared baking sheet.
In a small bowl, whisk together the Dijon mustard, dried parsley, garlic powder, remaining sea salt, and black pepper.
Spread the herb-mustard mixture evenly over the top of the salmon fillet to create a thick crust.
Slide the salmon into the oven during the last 12 to 15 minutes of the potato's cooking time, roasting until the fish flakes easily with a fork.
Remove both from the oven; slice the potato open lengthwise and fluff the interior with a fork.
Top the potato with the Greek yogurt and fresh chives, then serve immediately alongside the herb-crusted salmon.