Chop up the zha cai and ginger in the food processor too.
Crush the garlic chips with your hands or with a rolling pin.
Put the chopped leek, ginger and zha cai, the crushed garlic chips, shichimi spice in a wok with the soybean oil and 100 g of sesame oil. Start heating over medium heat.
Mix lightly to blend all the ingredients in the oil.
It will start bubbling after 3 to 4 minutes. When it comes to a boil, turn down the heat to low, and simmer gently for 30 to 40 minutes.
Turn the heat off and leave to cool.
When it has cooled down a bit, add the rest of the sesame oil (100 g), sugar, salt and soy sauce, and mix well.
It's finished. I divided it in several jars for ease of use. It can be eaten right away, but it will become milder after 2 to 3 days.
If you cover each jar with plastic wrap before putting on the lid, the jars won't get oily and the lid will be easy to open.
It has tons of chunky ingredients. Mix well before using.
You can use it as-is for gyoza dumplings, but the spiciness will be neutralized a bit if you mix it with some vinegar and/or soy sauce.
Story Behind this Recipe
I saw them spooning chunky ra-yu over rice, and I wanted to order the ra-yu they were using but I couldn't. So, the only thing to do was to make my own.
If you don't have soy bean oil you can substitute regular vegetable oil, but I do recommend using soy bean or sunflower oil. Be sure to add the sugar, soy sauce and salt after letting the oil cool down a bit, otherwise it will splatter.