Season beef with salt and black pepper; set aside.

Heat 2 tablespoons oil in a skillet over medium heat; add diced onion and garlic. Cook until softened, about 5 minutes; transfer to a 6-quart pot. Brown beef chunks in the skillet, individually, on all sides; place in the pot.

Add tomatoes, quartered onion, olives with brine, bouillon cubes, bay leaves, and crushed peppercorns to the pot; bring to a boil. Stir in ketchup; reduce heat to medium-low and simmer 1 hour.

Remove beef from the pot; set aside. Add bell pepper to the pot; simmer 30 minutes.

Meanwhile, heat remaining 2 tablespoons oil in the skillet; add potatoes. Cook until golden brown; transfer to the pot.

Slice beef against the grain; add to the pot. Stir and cook, 5 minutes. Whisk corn flour and water together in a small bowl; stir into sauce to thicken if its too thin.