Creating Japanese Beef Curry is straightforward if you follow these simple steps:

1. Heat Oil: In a large pot, heat the vegetable oil over medium heat.
2. Sauté Onions: Add the sliced onions and sauté until they become translucent, about 5 minutes.
3. Brown the Beef: Add the beef pieces to the pot, browning them on all sides for about 5-7 minutes.
4. Add Carrots and Potatoes: Stir in the sliced carrots and diced potatoes, mixing everything well.
5. Pour in Water: Add the water (or beef broth) to the pot, bringing it to a boil.
6. Simmer: Once boiling, reduce the heat to low and cover the pot. Let it simmer for about 20 minutes, or until the beef and vegetables are tender.
7. Add Curry Roux: Break the Japanese curry roux into pieces and stir it into the pot, mixing until fully dissolved.
8. Simmer Again: Allow the curry to simmer for an additional 5-10 minutes, stirring occasionally, until it thickens.
9. Taste and Adjust: Taste the curry and adjust seasoning if necessary.
10. Serve: Remove from heat and serve hot over steamed rice or with bread.

These steps will guide you in creating this wonderful dish effortlessly.