In a large bowl soak beans in cold water to cover by 2-inches for 1 day. Drain beans and halve onion. In a 5 quart kettle
simmer beans, lard or oil, onion, and epazote, if using, in water to cover by 2-inches, covered, 45 minutes, or until beans are almost tender. Add salt and
simmer beans until just tender, about 15 minutes more. Beans may be pre
pared up to this point 2 days ahead and chilled in cooking liquid, covered. Drain beans in a colander.
Chop bacon and in a large heavy skillet cook over moderate heat,
stirring, until
browned. Add beans, salsa, beer, and salt to taste and cook,
stirring, until most of liquid evaporates, about 10 minutes. Beans may be made 2 hours ahead and kept at
cool room temperature. Reheat beans before serving.