Heat oil in a large pot over medium-high heat. Add the onions and cook until soft, about 6 minutes. Add the garlic and some salt and pepper and cook about 1 minute.
Add the beef cubes to the pot. Stir in paprika. Cook until browned, about 6 minutes.
Add 2 cups cold water, cover with a lid, reduce the heat to medium and cook for 45 minutes.
Remove the lid and add the potatoes, carrots, tomatoes and green peppers, cover and stew until the beef is tender, about 30 minutes more, stirring occasionally. Adjust to taste with salt and pepper.