Heat the extra virgin olive oil in a large pan over medium heat. Add the garlic and ginger and cook for 1–2 minutes until fragrant. Stir in the sliced onion, season with salt, and add the water. Cover and cook until the onions are soft and translucent.
Add the butter and let it melt completely. Stir in the flour and cook for 1–2 minutes to form a roux.
Add the curry powder, ketchup, Worcestershire sauce, and sugar. Mix well. Pour in the tomato juice and stir to combine.
Add the water, bouillon cube, instant coffee powder, and salt.
Bring to a simmer and let the sauce thicken, stirring occasionally, for 10–15 minutes. Adjust seasoning as needed.
Make the Chicken Katsu:
In a bowl, mix salt, garlic powder, white pepper powder, and flour, then add the egg and water to form a wet batter.
Slice the chicken breasts into thin cutlets and tenderize with a meat mallet.
Dip the chicken into the egg batter, then coat it with panko breadcrumbs, pressing the crumbs on to adhere.
Heat oil in a large pan over medium-high heat. Fry the breaded chicken cutlets at 350°F (176°C) until golden brown and cooked through, about 3–4 minutes per side, until the internal temperature reaches 165°F (75°C).
Transfer the cooked chicken to a plate. Slice the chicken into strips. Serve the chicken katsu over rice with katsu curry sauce and a side of salad.
Notes
Form the Roux Gently: I always stir the butter and flour together for at least a full minute to get a smooth paste before adding the liquids. It helps the sauce stay velvety without lumps.Let the Sauce Simmer: I give the curry sauce a full 10–15 minutes on low heat, stirring every so often, until it thickens just right and the flavors really come together.Build the Batter Right: I mix the egg, flour, and seasoning until it forms a thick, sticky batter; it makes the panko stick so much better.Check the Oil Temperature: I use a thermometer and wait until it hits 350°F (176°C) before frying. That’s my sweet spot for crispy chicken without overcooking it.