One of my favorite cooks is reverse searing Santa Maria style tri-tip on the kettle. Like the gent above said, I'll put a charcoal basket on one side of the kettle, fill it up, and place 6 to 10 lit briquettes on top of those, depending on the outside temperature. A wood chunk or two will go on the charcoal for smoke, and the tri-tips will be of the other side of the grill, with their thickest sides facing the heat. I'll have the bottom dampers at about 50%, and the top anywhere from 25 to 75% open to keep the temp right around 275*F. About 5 minutes before I'm ready to take the tri-tips off the smoke (for a 10 minute rest), I'll light up some lump charcoal in a chimney for the searing. The tri-tips come off, get loosely covered in foil to rest, and then I dump the lump charcoal (hotter than hell) into two charcoal baskets in the center of the grill. I keep it in the baskets so it stacks up closer to the grill level; after the tri-tips rest, I want to sear them as quickly as possible so I'm not 'cooking' them all over again. So, after the rest, the tri-tips get a quick brush w/ olive oil, get seared for a crispy finish, and go straight to the cutting board. After reverse searing them like this, my wife won't let me cook tri-tip any other way again.