Heat the oil in a large saucepan and gently fry the onion in the oil for 4 to 5 minutes or until soft. Add the garlic, chile, peppers and mushrooms and cook for five minutes. Cover and cook the mixture for 15-20 minutes over a very gentle heat. Add the cooked beans, potato, paprika, thyme, tomato puree and miso to the stew. Simmer gently for 30 minutes, adding a little bean liquid if necessary. Season with salt and pepper and serve hot with rice or noodles. Serves four. Nutritional analysis per serving: 289 calories, 4.6 grams fat, 0 milligrams cholesterol, 111 milligrams sodium; 14 percent of calories from fat.