Peel the taro roots and cut into 1 cm thick round slices.
Thinly slice the onion.
Cut the bacon up into small chunks.
Warm a frying pan on a medium heat. Melt the butter in it and then add the onions and bacon and stir-fry until the onions have wilted. Season the mixture with salt and pepper, then continue to cook.
Add the taro roots along with the cooking sake, soup stock cube and water and then cover the pan with a lid and simmer on a low heat for 20-25 minutes.
Add the miso. If the mixture looks like it contains too much water then remove the lid and simmer on a high heat to reduce the amount of liquid. Be careful not to burn anything.
Transfer everything to a gratin dish then pour over the white sauce, green onions and cheese in that order. Cook in the toaster oven or grill for 15-18 minutes.
It's ready. Eat it whilst it's hot.
Here are 2 recipes for the white sauce:
Simple White Sauce with Pre-Cut Mochi (Recipe ID: 2069661) & Simple & Foolproof White Sauce (Recipe ID: 2027888).
Story Behind this Recipe
I got my hands on lots of taro roots! Simmered taro roots are nice, but I wanted to try using them in a delicious Western-style recipe.
Taro roots are quite viscous so keep an eye on them whilst simmering. If you cut the taro roots into slices half as thick as written then they will cook much faster. So try it when you're in a hurry.