Gather all the ingredients. For curry roux, you will need to break into cubes and use 2 pieces. Prepare dashi.
In a large frying pan, heat oil on medium-high and sauté onion until soft, about 7-10 minutes.
Turn off the heat and add 2 cubes curry roux. Using chopsticks or wooden spoon, dissolve the roux completely. Heat the curry on medium high for 10 minutes. Make sure you stir once in a while so the curry will not get burnt on the bottom.
Meanwhile, Boil a lot of water in a large pot and cook udon for 2-3 minutes and drain well.
Serve udon in a bowl and pour over the curry. Top with green onion and Ito Togarashi (chili pepper threads).
Japanese curry roux: Homemade recipe, click here.
Recipe by Namiko Chen of Just One Cookbook. All images and content on this site are copyright protected. Please do not use my images without my permission. If you’d like to share this recipe on your site, please re-write the recipe and link to this post as the original source. Thank you.