Leftover turkey, mashed potatoes, and gravy find new life in this decadent and towering Hot Turkey Katsu Sandwich. The mashed potatoes and turkey get cozy in a katsu-inspired croquette-ish patty, while the gravy gets a Japanese-style curry makeover. The two meet on top of a thick slice of bread piled high with shaved Brussels sprouts in place of the more traditional green cabbage for some added festive flair.
Japanese curry powder can be substituted for Madras curry powder.
Place the turkey, mashed potatoes, and egg yolks in a large bowl. Stir to combine.
Form the mixture into four patties. Transfer them to a baking sheet lined with parchment paper and chill for 30 minutes.
While the patties are chilling, make the curry gravy. Pour the neutral oil into a large skillet over medium heat. Add the onion and salt and sauté until just translucent. Stir in the pear and sauté until the pear starts to breakdown.
Stir in the curry powder and add the gravy. Bring the mixture up to a simmer and stir in the Worcestershire sauce and peas. Continue to cook until the peas are heated through. Keep the gravy warm until ready to serve.
Retrieve the turkey patties from the fridge. Working with one at a time, roll the patties in cornstarch before dunking it in the egg and coating it in the panko breadcrumbs. Repeat with the remaining patties.
Heat 2-inches of neutral oil over medium heat in a large cast-iron skillet. Add the patties and fry until golden on both sides, about 3 minutes per side. Transfer the fried patties to a plate lined with paper towel. Set aside to drain.
Spread mayo on each of the pieces of toast. Top them with the shaved Brussels sprouts and add a piece of turkey katsu to each. Cover the sandwiches with the curry gravy and serve immediately.