Ramp the heat up on the cooker then hit it with a wire drush to remove the tough stuff. A weed burner would do nicly. Then either take it to the sink or a bucket of soapy water in the yard.
Slappin that bass like some delerious funky preist!!!
UDS, Half Pint (Mini UDS), Weber, ProQ 20, Kegrilla
*250 gallon cooker- 'The Meat Beast!!'*
British BBQ Championships
Grand Champion 2008
British BBQ Society - Southern Championship
Grand Champions 2009