Although I have a rough basic process for making Japanese Curry, I can't say I've ever made it exactly the same twice. The spirit of experimenting probably comes a lot from the fact that these block curry rues are so bulletproof, you'd actually end up with something decently tasty if you had simply simmered them down with hot water (not that I recommend it). Of course incorporating your favorite vegetables and choice of protein gives the dish the umami depth it really deserves.
Last weekend I felt like doing a healthier pulverized veggie style with also maybe a mild tomato tartness. Used a whole onion, about two carrots and 1/3 can of tomato paste (in that smaller tin). Skipped the long process of caramelizing the onion into that sweet brown paste because I couldn't be bothered the day (though I highly recommend). Instead, sauteed everything into a light sweat, then simmered away on low.
When I felt the veggies were cooked, added the block curry rue. As for kakushiaji (hidden flavor agents) everyone seems to have their little secrets to give it that personal touch. I've heard most of them, from adding shavings of chocolate, to a pinch of instant coffee granules, to leftover Fukushinzuke pickle syrup (particularly seen in the "nothing goes to waste" frugal but bold Japanese Maritime Self Defense Force recipe). Btw, did you know Japanese Curry has its roots from Great Britain (specifically the Navy)?
My recent fascination has been to add whole Cardamon and Cumin seeds. I'm sure the inspiration from some random older Japanese television program. I also add a couple tablespoons of Soy Sauce. After all this is Japanese Curry... :)
Other commonly recommended 101 Basics is to mix two brands of Curry Rue, preferably also in different spice levels. This day I used a blend of House's Kokumaro medium, and S&B's Golden Curry extra hot. Again, gives your curry that little additional complexity.
The Kakuni braised pork belly was an impromptu decision to make Sunday night. (So much for the healthier curry, haha.) I seasoned it with a pinch of Curry Powder instead of Star Anise and ended up being a nice touch for the meal which I'd have the day next. The first plate I enjoyed more the contrast between the curry and flavor of the pork. The naturally sweet veggie centric curry with a slight tomato tartness complemented really well the richer Kakuni that was wiggly soft and chopstick tender. My second, I stewed the leftover 1/2 kakuni block into the curry itself for a more incorporated taste. All good.
My personal method for making Rafte style (Okinawan Pork Belly) Kakuni I'll have to go over on another post. It starts out more as a low and slow simmer than an actual braise, where I finish it in the convection oven in foil.
Stewing Japanese Curry is fun, especially on a lazy Sunday. Tasting the curry throughout the day and witnessing the flavors slowly mature over time. Because I wanted the vegetables to almost disappear into the stew, I ended up simmering this one for an unusually long time. Either way, always will taste better rested overnight in the fridge as it lets all the flavors set. The difference is night and day (no pun intended).