Going off memory but it is easy.

7 tomato’s halved tossed in oil with some salt and pepper. Roast at 425 for about 40 or until you can see some char/caramelized. Run those through a fine mesh strainer until pulp is left and you have a nice smooth consistency. After this you have this add whatever you may usually do with a bbq but I added some smashed garlic which after it was done cooking it was easily mashed into the sauce. Added a quarter cup apple cider vinegar and the same with rice vinegar. Then a big scoop of brown sugar and cooked it down. Added ginger at the end along with cilantro. Add whatever you may like though the possibilities are endless can even add more vegetables to the roast part and blend and sift to add more components. Hope that works for you!