The idea of further preparing niboshi before making dashi stock has always interested us because the various steps involved are up to the discretion of the chef at any point. Some choose to carry out every single step, whilst some decide based on the quality of niboshi at hand. 

At this site, we’ve always had a keen interest replicated the taste and techniques used at famous restaurants, and have found the preparation of niboshi dashi similar to the process of roasting sesame seeds in that the many small steps carried out with care contribute to a large difference in taste of the final product. Many a time we have brought the same high quality ingredients that we have heard a certain restaurant uses, only to fall short replicating the taste and mouthfeel of the dish simply due to minute differences in preparation. 

Below, we show the typical ways that niboshi can be prepared before using to make stock, with some brief notes that hopefully allow you to make better decisions surrounding niboshi dashi preparation.

Head and Innards Removal

The first steps taken to clean niboshi for making dashi is usually the removal of either the heads or innards or both together. As the head contains the gills of the fish, it has a high proportion of dried blood inside which contributes to an iron-like tannic taste to the dashi. Furthermore, as the blood oxidises, it can make the stock cloudy as well as take on a brownish tinge. 

The main fishy smell that people associate with niboshi dashi actually comes from the innards, which also contribute a bitter taste. Because of this, we recommend removing the innards from niboshi if you have time to go through such a labour intensive process. If you have very fresh niboshi, it’s sometimes possible to pull out the innards along with the head in one piece. Failing to do so, you’ll have to cut or pinch open the belly to pull out the innards after removing the head. In fact, we have found that the flesh surrounding the belly can also contribute a slightly bitter taste. Therefore, if you’re willing to discard quite a large proportion of niboshi, by removing the belly flesh, head and innards, you can try to create an extremely clear expression of niboshi dashi. 

Of course there are exceptions to this. The process of preparing niboshi this way is very time consuming, and also very costly. Restaurants that cater to a high volume of customers at a cheap price may choose to make dashi from whole niboshi without any preprocessing. Sometimes, the stronger fishy taste of the niboshi is actually desirable. For example, some recipes for ramen and tsukumen with very strong and thick soups, like ‘cement’ ramen, would benefit from using whole niboshi to allow the taste of niboshi to come through in the final dish. 

Additionally, some restaurants deliberately choose to source niboshi sardines that are as small as possible, as small fish tend to have less developed innards, and also a smaller proportion of innards to flesh, thus allowing them to create dashi without too strong a bitter taste. There are also certain types of niboshi, like tai niboshi, which tend to be used in dashi whole, even though they are quite large. This is possibly due to tai niboshi’s comparatively light taste. 

From our experience, the niboshi heads do not actually contribute a bitter taste to the dashi as some resources say. However, removing the heads is probably the easiest way to access the innards. We recommend trying to make dashi with and without heads and innards for you to judge for yourself.

In much rarer cases, some chefs choose to split niboshi open into two halves, allowing you to not only remove the head and innards with ease, but also remove the spine. From our experience, removing the spine does very little to affect the taste of the dashi. The main noticeable difference is that splitting niboshi allows you to remove any innards and guts to a much cleaner degree than otherwise possible. Weight-wise, the same amount of whole niboshi versus only niboshi flesh alone would yield a far stronger stock simply due to using more fish. 

In our article on how to store niboshi, we talk about freezing as a fantastic way to extend the shelf life of niboshi. Similarly, it’s possible to behead, gut and split the niboshi before freezing it, saving you time later. 

Washing Niboshi

Some places recommend giving the niboshi a quick rinse and soak before using. We have found this to be unnecessary if using fresh high quality niboshi. We never rinse or soak our niboshi if we intend to behead and gut them. However, if using whole niboshi that may not be in its freshest state, we have found bits of skin and scales flake off and thus a quick rinse with water is sometimes merited. 

On a side note, the usual 30g to 60g of niboshi used to make a litre or two of niboshi dashi is so small that the effect of rinsing and soaking can be negligible. However, for much larger batches of soup like that of ramen, it can be worth the extra effort. 

Dry Frying Niboshi

Just like how frying spices before making a curry better brings out the aromas and flavours, dry frying niboshi for 4 to 5 minutes until fragrant can greatly improve the flavour of your dashi and reduce the overall fishy taste. It is a particularly useful technique for niboshi that is starting to oxidise as it can revive the taste of stale niboshi. 

While this is usually done over a medium-high heat without any additions, some chefs even recommend adding a couple of drops of sesame seed oil to boast the flavour. This imparts a nutty taste to the resulting dashi which nicely compliments the natural taste of niboshi. The suitability of this highly depends on your end goal. For clear soups or dipping sauces, we dislike the additional flavour as we feel it distracts from the taste of fish. Additionally, it results in tiny droplets of oil that float on the surface of the dashi (which can be skimmed off).

We think that this technique is best reserved for niboshi close to the end of its shelf life, or niboshi that has been frozen. For niboshi that has been gutted and split, reduce the frying time slightly. If fried for too long, the resulting dashi will taste closer to cooked fish soup and the original flavour of niboshi will be lost.