Preheat your oven or grill to 450 degrees F.
Cut the onion in half and place it on an oiled roasting sheet with the whole tomatoes, pepper and garlic.
Roast the vegetables in an oven or on the grill for 15-20 minutes at 450 degrees F. The vegetables are finished roasting when the skin on the tomatoes starts to pull away.
Cut the top off of the pepper and remove the seeds if you want the salsa to be milder. Cut the tomatoes in half and the onion into smaller chunks.
Add all ingredients into a food processor and then pulse until you have reached your desired consistency.
Pour the salsa into your favorite dish and enjoy!