Heat the oil over medium heat and sauté the diced onion until soft and deeply golden. Add the brown sugar, Dijon mustard, tomato paste, garlic powder, paprika, salt, black pepper, and onion soup mix. Stir well and cook for one to two minutes, until the mixture is fully incorporated and fragrant.

Pour in the bourbon and continue cooking, stirring, until the alcohol has evaporated and the mixture thickens slightly.

In a 9×13-inch baking pan, add the washed beans and barley, then scatter the diced potatoes over the top. Add the onion and spice mixture and mix well to combine. Pour in seven cups of water, cover the pan tightly with foil, and bake at 350 degrees Fahrenheit (175 degrees Celsius) for three hours.

Remove the pan from the oven, stir well, and add one to one and a half cups of water as needed. Cover tightly and return to the oven at 300 degrees Fahrenheit (150 degrees Celsius) for an additional hour, or until all the beans are completely soft.