For black beans, says the kitchendude:

Soak overnight (24 hours); drain; add benas, and fresh water to cover by 2-3 inches, into your pressure cooker; add nonsalt seasonings (sauteed onions, herbs, etc); pressure cook for 1.5 hours; then add salt and salted seasonings like bacon, and fats, and simmer for a while longer to combine. Munch.