I already announced it last week: we are going to make kosho today. Don’t be embarrassed if you have never heard of this magical substance, I only discovered it a few years ago, and moreover by chance.
When I walk through an Asian supermarket, I sometimes want to throw a random bag, package or jar into my shopping cart, just out of curiosity. Sometimes, when I get home, such a product turns out to, how can I put it respectfully, not entirely match my taste preferences. From Chinese grass jelly for example, a translucent, slightly bitter black pudding that is sold in a can and seems to be very popular for its cooling properties, spontaneously gave me chills. But sometimes it is also love at first bite. That was the case with a small glass jar containing a somewhat grainy, yellow-green paste: yuzu kosho.
Also read
Non-toxic yellow boys
Yuzu is a pale orange citrus fruit with a thick, irregular peel and the shape of a mandarin. Although it is also used in other Asian cuisines, it is perhaps most popular in Japan. For example, yuzu juice is one of the most important seasonings in ponzu, a dipping sauce served with tempura. For yuzu kosho, the peel of the fruit is grated and mixed with finely chopped chili peppers and salt. The resulting paste is then allowed to ferment, creating a tingling, fresh and tart condiment.
Now, fresh yuzu is very difficult to get in the Netherlands, and if you do find it, the fruit is shockingly expensive. This winter I bought a single copy from my extremely well-stocked vegetable jeweler in The Hague (Rutten, for those who want to know) and paid around 5 euros for it. There appeared to be hardly any juice in it, but the peel was bursting with essential oils, so I scraped it off with my finest grater and used it in a kosho consisting of lemon, mandarin, orange and lime peel. Because that’s the good news: kosho can also be made from other types of citrus fruit.
What can you do next with kosho? First, you could serve it with raw fish (such as sashimi). It gives the same kind of sharp kick as wasabi. Secondly, you could mix a little kosho, say 2 level teaspoons, with olive oil, say 2 to 3 tablespoons, and brush the skin of a (piece of) fish with it, then grill it in the oven. Thirdly, you can stir some kosho into mayonnaise or crème fraîche and serve this sauce with grilled vegetables. This was how I initially fell in love with kosho: 2 level teaspoons to 125 ml crème fraîche, with strips of pumpkin from the barbecue.
Kosho also works great in a simple lemon dressing: for a jar full, put 100 ml fresh lemon juice, 300 ml olive oil, 1 large clove of garlic, 2 level tsp kosho, 2 tsp honey and 2 tsp dijon mustard in the blender, add salt and pepper and mix into an emulsion. (Or use a hand blender.) The dressing will keep for 1-2 weeks in the refrigerator, and you can also use half and half olive oil and a more neutral oil such as avocado oil or sunflower oil.