Pour the beer into the water in a large bowl. Preferably one that is easy to pour out of, as it is all going to go into a Ziploc once dissolved.

Add all of the brine ingredients and whisk together to dissolve.

Put the pork in a large, heavy duty Ziploc bag. Pour the brine over the pork.

Seal the bag and put the Ziploc into another bowl just in case. Let the pork sit in the brine for at least 8 hours or overnight.

Combine the mustard, brown sugar, salt and pepper in a bowl.

Pull the pork out of the brine and dry off with paper towels. Spread the mustard mixture all over the pork.

Put the pork in a saute pan over medium-high heat coated with a little olive oil. Cook for two minutes or until all sides are brown.

Bake at 325 degrees for an hour or until the meat reaches 160 degrees. Let stand for at least 10 minutes before you slice it.

To make the Horseradish Mustard Sauce:
2 1/2 Tablespoons horseradish
5 Tablespoons sour cream
1 Tablespoon mustard

Put all of the ingredients in a bowl and mix. You can make this a few hours ahead of time and let it chill in the refrigerator.

Slice the pork thinly as possible and put on a roll. Serve with the Horseradish Mustard Sauce.