Turn your grill into a smoker using wood chips that are available at the grocery store (usually by the charcoal). Soak the wood chips in water for 30 minutes. Make a packet of wet wood chips using aluminum foil. Open the top of the packet and place the packet directly on your coals or gas rocks. When the wood chips are smoking heavily, place the tomatoes and garlic on the grill and smoke until blackened all over. The garlic should be placed on the coolest part of the grill. Transfer the tomatoes to a bowl. Let the garlic smoke until softened, about 40 minutes. Set aside to cool. Squeeze the garlic cloves into a small bowl and set aside.