In a pot over medium heat, add oil. Pan fry potatoes and carrots. Remove from pan and drain on paper towels.
On the same pot and oil. Add onion wait until translucents and add garlic and cook.
Add beef. (Fyi, I did marinate the beef for 10 minutes but it is optional and add a squeeze of lemon.)
Add soy sauce and oyster sauce. Give it a good mix so the sauce will penetrates into the beef.
Add tomato sauce and water. Stir until well distributed and bring it to boil.
Adjust the heat to lower heat and wait for 45 minutes to 1 hour until the beef is tender. Add more water as needed if the sauce is drying out before the meat is cook.
Add potatoes, carrots and bell peppers and stir for 2 minutes.
Add banana ketchup, sweet peas and wait for 5 minutes until the vegetables are soft.
You can add salt and pepper to taste.