Heat a large pot on medium. Add 1 tsp cooking oil and add 150 g thin sliced pork belly. Fry until seared on both sides.
Once the meat is seared, add 500 ml dashi stock to the pot with 3 tbsp soy sauce, 2 tbsp mirin and 1 tsp sugar. Mix and bring to a boil, once boiling lower the heat to a simmer.
In a small bowl, mix 3 tbsp S&B curry powder and 1 tbsp potato starch. Once combined, add 5 tbsp cold water and mix it into a thin curry paste. (It have the thickness of pancake batter.)
Pour the curry paste mixture to the pot and whisk to incorporate it into the broth.
Add 100 g green onion and 50 g shimeji mushroom(s) to the pot. (You can also add 8 slices kamaboko fish cake and 2 fried tofu pouch (aburaage) here if you are using them.)
Simmer for 15 minutes or until thickened, stir occasionally.
While the soup is simmering, cook 2 portions udon noodles in a separate pot following the instructions on the packaging. Once cooked, drain in a colander and rinse with freshly boiled water.
Transfer the cooked udon to serving bowls and pour the curry soup over the top. Garnish with chopped spring onion and shichimi (Japanese chili pepper).
Enjoy!