This is a very traditional japanese curry recipe. The packets of curry roux don't always tell you everything you need to know on how to use the roux. My only suggestions is to cook around 30minutes or so, not 40-50minutes. The vegetables should be very tender and the meat cooked through. I halved the recipe and found half of a halfpack of curry roux was about right, although I needed to add a bit of extra boiling water as the sauce got very thick.