Get your grill going with mesquite wood. You do not have to wait for grill to cool down to start roasting since you want the high temprature. Place garlic cloves in aluminum foil and wrap loosely. Place onions, garlic, tomatoes, and jalapenos (optional) on grill and turn every few minutes until well chard. Tomatoes will be done first. Make sure the tomatoes go on the hottest part of grill. You do not want to cook the tomatoes as much as you want to burn them on the outside. Let ingredients cool. Cut your avocados in half and scoop out and mash in a large bowl. Mince garlic and chop cilantro, tomatoes, onions, and jalapenos and add to bowl. Salt and pepper to taste. Don't be surprised if you have to add a lot of salt. Avocados tend to be bland. Once the guacamole taste well seasoned, add the juice of one lime. This is not for flavor but only to keep guacamole from turning brown. Cover bowl with plastic wrap and let guacamole rest for a few hours in refrigerator.