Rub the tomatoes with juice through a sieve into a saucepan. Put on medium heat, cook 10 minutes.
Peel the garlic. Cut hot pepper in half, remove seeds. Heat the pan, put garlic cloves, hot pepper and black peppercorns on it. Fry, stirring, 2 minutes. Transfer to a serving dish, let cool slightly, then transfer to a blender and puree. Add tomatoes, oregano, cumin and beat until smooth. Pour into a saucepan.
Place the tortillas in the same pan. Fry, pressing with a spatula, for 2 minutes. from each side. Remove from heat, cool slightly, then break into small pieces.
Add corn oil to the saucepan with the tomato paste. Cook, stirring occasionally, 5 minutes. Pour in 4 cups of water, add the finely chopped potatoes and bring the soup to a boil. Cook 10 min.
Add beans and corn. Cover with a lid, cook for another 5 minutes. Before serving, add tortilla pieces.