old fashioned boston baked beans

Ingredients

• 2 pounds navy beans,dried
• 2 quarts cold water
• 1 large onion, sliced
• 1 tablespoon kosher salt
• 4 teaspoons cider vinegar or juice from your pickle jar
• 1 teaspoon dry mustard
• 3 heaping tablespoons brown sugar, firmly packed
• 1/2 cup dark molasses
• 1/4 cup ketchup
• - freshly ground black pepper to taste
• - hot water if needed
• 1/2 pound salt pork