How to Make It
Combine bell pepper, onion, tomato, tomato paste, garlic, ginger, seasoning cubes, chile, and curry powder in a high-speed blender. Process on low speed, gradually increasing speed to high, until smooth, about 50 seconds.
Transfer bell pepper mixture to a large pot; add oil. Cook over low, stirring occasionally, until sauce is the consistency of a thick gravy and is reduced to about 3 cups, about 1 hour and 10 minutes. Let cool completely, about 1 hour.