In a saucepan, heat the oil over medium heat and saute the onion, garlic, hot pepper and cumin for 2 minutes. Add the vegetable stock and tomato juice,and let simmer for 5 minutes.
Mix the cornstarch with a bit of cold water and add to the sauce while stirring. Remove from heat and set aside.
In a bowl, mix the tomato, beans, potatoes, coriander and cheese. Divide this mixture among the tortillas, cover with a large tablespoon of the sauce and roll up. Place the enchiladas in a lightly oiled rectangular ovenproof dish.
Cover the enchiladas with the remainder of the sauce and cook in the oven at 350 F for 15-20 minutes. Serve immediately accompanied with your favourite garnish or dip.