A katsu curry sauce mix is a packet of powder you stir into water to make a thick, mild curry sauce. It is the quickest route to the sauce that goes with katsu chicken, and most supermarkets sell one.
Mix, jar or roux block
A mix is the cheapest and quickest option, but you need to make the sauce from scratch in a pan. A ready jar is the most convenient, and it costs more per serving. Japanese curry roux blocks are a third option. They give a richer, thicker sauce, and they are usually sold in larger boxes.
Where to find it
Look in the world food aisle, in the Japanese or curry section. Some stores also keep mixes near the stock cubes and gravy granules. If you cannot find it, check the Japanese shelf near the tonkatsu sauce.
What to check on the pack
Read the serving size and the water amount. Packs differ, and using the wrong water ratio gives a sauce that is either too thin or too thick. Check whether the mix is vegetarian, since some contain meat extract.
How to make it
Follow the pack, which usually asks you to whisk the powder into hot water and simmer for a few minutes until thick. Add a little more water if the sauce sets too firmly once cool. Serve it hot over fried chicken or pork cutlets with rice.
Storage
Keep the packet sealed in a dry cupboard. Once you have made the sauce, store leftovers in the fridge and eat them within a few days.
For the crumbed meat to serve with it, see our chicken katsu recipe. For the sweet sauce many people add on the side, read our tonkatsu sauce guide.