In Nanban, I spend a few pages detailing some of the most important ingredients for Japanese home cooking. I begin with five essential items: soy sauce, mirin, rice vinegar, miso, and dashi powder. With these five ingredients in your cupboard, you will be able to create a huge range of Japanese dishes, sauces, and seasonings by combining them in different ways, and almost all of them are now widely available at big supermarkets.
I would highly recommend buying a good-quality Japanese brand of soy sauce; Kikkoman is common, and though it is more expensive, its flavor is superior; balanced, fresh, and aromatic. For mirin and rice vinegar, usually own-brand supermarket varieties are absolutely fine, but if you have a choice, I would recommend Takara Hon Mirin and Clearspring Brown Rice Vinegar. With miso, there are so many varieties and flavors out there, I’d suggest you buy a few to try, and choose whichever you like best. I like Hikari Awase Miso as a go-to, all-purpose miso; it is very well balanced between the light, sweet freshness of white miso and the rich, fruity, malty flavor of red miso. It works well in just about everything, including desserts. Dashi powder is probably the only ingredient you’ll have trouble finding at a big supermarket, but any Asian grocer should have it, and it really is fundamental. I prefer Shimaya, but this is also often a matter of buying a few kinds and figuring out which you like best.
(By the way, it is far, far more common for home cooks in Japan to use dashi powder instead of fresh, homemade dashi, since it is so convenient, cheap, and generally quite tasty. But if you’d prefer to make dashi from scratch – and everyone should try it at least once – you will need kombu and katsuobushi instead.)
On top of these ingredients, I also recommend two more if you’d like to inflect your Japanese cooking with a distinctly southern accent: yuzu-koshō and shochu. Yuzu-koshō is a highly aromatic condiment made by pounding fresh yuzu peel together with hot chillies and salt. After a period of ageing, the resulting paste has a delightfully resinous, herbal aroma and a powerful tangy-pungent-salty flavor. Just a quarter of a teaspoon or so is all you need to lift a bowl of porky ramen. It also tastes great with chocolate. Kyushu is known generally for its delicious citrus fruits and its chilli-spiked dishes like karashi mentaiko and motsunabe, and specifically for its yuzu-koshō, so buy a jar and experiment with it to get an idea of what sets southern Japanese food apart.
Shochu, the spirit of Kyushu, is sometimes used in cooking, but really you should just buy a bottle to have with the meal. It is stronger than sake, distilled rather than just fermented, and can be made using a variety of methods and a virtually limitless range of ingredients. In Kyushu, the most popular shochu is distilled from sweet potatoes, which give the finished product a sort of nutty and sometimes smoky flavor. The aroma of any given shochu is also strongly influenced by what kind of mold (kōji) is used to kick off its fermentation. For example, ‘white’ mold tends to be cleaner, fresher, and more floral; ‘black’ mold is often richer and earthier, reminiscent of fermenting fruit. There are two good entry-level shochu I’d recommend, depending on your taste for booze. If you like the light, clean flavors of vodka or premium sake, go for Unkai, a smooth, bright, floral buckwheat shochu that works very well in cocktails. If you’re more of a single malt whisky fan, try Kuro Kirishima, a black mold sweet potato shochu with a strong, funky, slightly peaty, overripe melon flavor. They will both be good for cooking, either in place of mirin or in recipes that call for it specifically, like tonkotsu, a sweet miso-and-shochu pork rib stew from Kagoshima.
Japan Centre still has the best range in the country for any of these ingredients, and they’ll deliver basically anywhere. But have a close look at your nearest big supermarket or your local Asian food shop. You might be surprised at what you can find.