Place a medium saucepan over a low heat and add 1 tablespoon of vegetable oil.
Add 1 sliced onion and fry for 5 minutes until the onions have softened. Turn off the heat.
Break up 1 S&B curry block (92g) and add it to the saucepan, crushing the pieces with a wooden spoon.
Measure 720ml of freshly boiled water (or 540ml for the mild curry block) into a jug and add 3 tablespoons of water to the saucepan, stirring well.
Add the rest of the water slowly and keep stirring until the curry block has completely dissolved.
If you want to include any extra vegetables like mushrooms or broccoli then add them to the saucepan now.
Turn the heat under the saucepan to medium and when the curry starts to boil, turn the heat down low, cover and simmer for 10-15 minutes.
Once the curry is ready, serve it over katsu chicken and rice.
Keep any leftover sauce in the fridge for up to 48 hours.
