While pellet grill is preheating, slice open tomatoes, onions, and peppers. Add them to a disposable pan, along with whole cloves of garlic, and toss with salt.
Place the pan in the smoker and let it smoke for about an hour and a half. Toss it a few times during the smoking process.
Remove from smoker and let cool. Add to food processor with cilantro and lime juice. Pulse until blended.
Serve immediately or refrigerate in a jar for 24 hours to allow all the flavors to meld together well.