Preheat the oven to 425°F. Line a baking sheet with foil. Drizzle 1 tablespoon of the olive oil on the foil and use your fingers to rub it over the surface.
Place the salmon on the foil, skin side down, and sprinkle evenly with a large pinch of salt. Spread the mustard evenly over the top of the salmon.
Put the remaining 2 tablespoons of olive oil in a small bowl and add the panko and a pinch of salt. Stir until the crumbs are evenly moistened, then pack them on top of the salmon.
Roast the fish until the bread crumbs are nicely browned and the blade of a dinner knife inserted into the thickest part of the salmon is hot to the touch, 18 to 20 minutes.
Cut the salmon into individual portions and serve.