Fry bacon til crispy, remove, chop and set aside. Add onions to skillet and saute til tender. Add cooked beans and 1 1/2 cups retained bean liquid. Add the sour cream, 1/2 cup shredded cheddar cheese, chili powder and salt. Mash til creamy. Stir in salsa, chopped bacon and top with 1/2 cup cheese. Serve warm or cold with tortilla chips or vegetables.