Rinse the beef rump roast under cold water, pat dry and cut into strips.
Rinse the bell peppers, cut in half, remove seeds and ribs, and cut into thin strips. Rinse the yellow tomatoes, cut into quarters and cut out the stalk. Puree the yellow tomato quarters with the vegetable broth in a blender.
Heat safflower oil in a pan and brown the beef rump roast all around. Add the bell peppers, and season with salt, and stir in the ginger powder.
Pour in the tomato puree, bring to a boil and cook over low heat for about 10 minutes.
Mix the potato flour in a little cold water and stir into the beef and bell peppers. Season with salt and pepper and serve as desired with steamed potatoes.