Drain the
beans, rinse, place in a saucepan and cover with cold
water.
Bring to the boil and boil rapidly for 10
minutes, then reduce the heat and simmer for 35-45
minutes until tender. Drain and rinse thoroughly under
cold running water.
Heat the oil in a saucepan. Add the
onion and fry gently for 5 minutes until soft. Add the
mushrooms and cook for 1 minute. Add the liver and
garlic. Cook, stirring, for 5 minutes.
Stir
in the chili powder and flour and cook, stirring
constantly, for 1 minute. Stir in the tomatoes.
Season
to taste with salt and pepper, then stir in the cumin.
Bring to the boil, add the beans, then cover and simmer
for 20 minutes.
Transfer to a warmed serving dish and
garnish with parsley sprigs.