Prepare the remoulade sauce by mixing mayonnaise, Dijon mustard, lemon juice, capers, and fresh herbs in a bowl. Stir until combined and creamy. Set aside in the fridge to chill.

Preheat your oven to 375°F (190°C). Place the salmon fillet on a parchment-lined baking sheet, drizzle with oil, and season with salt and pepper. Bake for 15-20 minutes until flaked easily and reaches an internal temperature of 130°F (54°C). Let cool before flaking into small pieces.

In a medium saucepan, melt butter over medium-low heat, then sauté the shallots for about 3 minutes until translucent. Add minced garlic and cook for an additional minute, then remove from heat.

In a large mixing bowl, combine flaked salmon, mashed potatoes, seasoned breadcrumbs, sautéed shallots and garlic, Old Bay seasoning, and Dijon mustard. Mix thoroughly, then form mixture into oval-shaped croquettes about the size of three tablespoons.

In a large skillet, heat oil to 375°F (190°C). Gently place croquettes into the skillet and fry for 2-3 minutes on each side until golden-brown. Use a slotted spatula to remove and drain on paper towels, sprinkling with salt.