Hi Anna, I have a recipe for dashi here: https://norecipes.com/how-to-make-dashi/ and where you can buy sake will depend on where you live. If you live in the US, you can order it online from Tippsy.

buy a steak and slice it very thin, if you put it in the freezer for awhile first its easier to slice

Thanks Patricia! I'm glad you enjoyed it!

Very good

Hi Mary, dashi just means "soup stock" in Japanese so just like there are different kinds of soup stock in western cuisine there are many different kinds of dashi. Shirodashi is usually a bottled concentrate which includes seasonings like salt, mirin, soy sauce, etc already mixed in. The idea is that you can use it as a convenient seasoning without adding other ingredients. You can certainly use it for this recipe, but you'll most likely need to dilute it with water and you'll also need to reduce the amount of salt and seasonings accordingly.

Hi Mary Ann, it will make it sweeter, but sure!

Hi Jon, I'm glad to hear you enjoyed it. The toughness was most likely the thickness of the meat, you can try to cook it for a little longer to compensate (though you may need to add more liquid). As for what you can do with the rest of the meat, how about Nikujaga? https://norecipes.com/quick-nikujaga-recipe/