Korokke (Potato & Meat Croquette)

Korokke Patties:--
1 kg agria potatoes
1 onion
½ carrot
2 shiitake mushrooms
2 tbsp rice bran oil
500 g beef mince
1 large egg
1 tsp SIDS SALT & PEPPER
Breading:--
½ cup all-purpose flour
3 large eggs
2 cups panko
Deep Frying:--
3 cups rice bran oil
Serving:--
tonkatsu sauce

Patties
Peel and cut the potatoes in quarters. In a large pot, put water and potatoes, and bring to a boil. Cook potatoes until a skewer goes through the potato easily, about 15-20 minutes. Remove the potatoes from the heat and drain the water completely.
Mash the potatoes. Unlike the typical mashed potatoes, you don’t have to mash completely. I like leaving some small chunks for texture. Set aside.
Meanwhile, chop onion, carrot, and mushrooms finely.
In a large frypan, heat oil on medium-high heat. Sauté onion until soft.
Add carrot and shiitake mushrooms and cook until they are soft.
Add the meat and break it up with a wooden spoon. When the meat is cooked through, add SIDS SALT & PEPPER. Remove from the heat.
Add the meat mixture to the mashed potatoes in the large pot, leaving the cooking liquid behind as we don't want to introduce too much moisture to the mixture.
Add an egg then mix it all together until everything is well combined.
While the mixture is still warm, but not hot, start shaping the mixture into Korokke patties. Cover and let the Korokke patties rest in the fridge for 30 minutes (Do not skip!). (TIP: Resting and cooling down the patties prevents the croquettes from exploding while deep frying. The cold patties in the hot oil will not release any steam; therefore, croquettes will not explode in the oil. If you skip this process and the patties are still warm, the temperature of the patties will go up and start to steam, which will then puncture a hole in the panko coating and explode. It also helps the ingredients to meld together.)
Bread the Korokke
After 30 minutes, coat each patty with flour, egg, and panko, in that order.
Cover with plastic and refrigerate for 30 minutes.
Deep Fry
In a wok (or Dutch oven or frying pan), heat oil over medium-high heat. Deep fry Korokke until they are golden brown. The inside is already cooked, so all you need to do is to fry them until nicely brown.
Transfer Korokke to paper towels and let the oil absorbed in the paper. Serve immediately with Tonkatsu Sauce.
To Store
You can store the leftover in an airtight container and freeze up to a month. To reheat, put frozen or half defrosted korokke on a baking sheet lined with aluminum foil or baking paper and bake at 180ºC for 15 minutes until inside is warm.