Texas-style Beef Brisket

6 to 8 lbs. brisket, untrimmed;

3 tbsp. chili powder;

1 tbsp. allspice, ground;

1 tbsp. celery seeds;

1 tbsp. coriander seeds, ground;

1 tbsp. garlic powder;

1 tbsp. mustard seeds, ground;

1 tbsp. dried oregano;

1 tbsp. smoked paprika;

1 cup beef stock;

Sea salt and freshly ground black pepper;