Heat the oil and butter in a medium size pot and caramelize the onion well.
Add minced garlic, micro-fined ginger, and apple cider, sauté for two minutes.
Stir in the flour and curry powder and cook for three minutes.
Slowly whisk in the rich chicken stock until combined (do this gradually to avoid getting lumps) on medium heat for 5 minutes.
Add the ketchup, Worcestershire, Garam Masala, cocoa powder, light brown sugar and bay leaf, bring to a low simmer for another five minutes.
Whisk in salt.
Remove from heat and pass through a chinois.
Serve immediately.
Notes
Caramelized onions are an essential part of perfecting a truly authentic Japanese Curry. Another important technique to remember is always toast your spices to release essential oils and aromatics. Japanese Curry just like any curry should take time to perfect.