If you haven't already make our remoulade sauce recipe.
Preheat the oven. Place salmon on a parchment lined baking sheet, then drizzle with neutral oil. Season with Kosher salt and freshly ground black pepper. Cook. Allow to cool for a few minutes, then flake the salmon and transfer to a large mixing bowl. Discard salmon skin.
In a small pan, melt butter over medium-low heat. Add chopped shallot and cook, stirring occasionally, until translucent. Do not let the shallots brown, adjust the temperature as needed. Add chopped garlic, stir, then cook.
To the salmon, add mashed potatoes, seasoned breadcrumbs, shallots, Old Bay seasoning, and Dijon mustard. Use a spatula or spoon to mix well. Take about 3 tablespoons of the mixture at a time, then form into an oval shaped croquette. Repeat with remaining salmon mixture.
When ready, heat enough oil in a pan to come up about ½-inch over medium-high heat. Add croquettes to the pan then cook until golden brown on all sides. Transfer to a paper towel lined plate or wire rack, then immediately season with a sprinkle of Kosher salt. Serve immediately with remoulade sauce!