Prepare Kamado BONO grill for direct cooking, light the charcoal, cover with the lid and wait until the temperature reaches 160 degrees Celsius. Adjust the top and bottom vents to maintain an even temperature. Place a pot in the grill in direct heat.
Blanch tomatoes in boiling water to make it easier to peel off the skin. Remove seeds and chop.
Combine all ingredients in a covered frying pan and cook over very low heat for about 30 minutes. Strain through a sieve to remove excess liquid. Optionally, blend with a blender. Roasted tomato sauce is ready.