Combine mustard seeds, celery seeds, bay leaf, peppercorns, hot sauce, vinegar, sugar, salt, garlic and water in a saucepan. Place over medium-high heat until boiling, reduce to a simmer, and maintain for 3 minutes. Turn off heat and add ice.
Cut pork butt into 2" cubes. Place in a large zip top bag. When the brine is cool, pour it in as well. Press out as much air as possible and seal the bag. Refrigerate for a minimum of 3 days, turning bag a couple of times a day.
Keeps 2 weeks in the refrigerator; after that, drain and freeze. Note that this is NOT edible as is; it still has to be cooked!