If you're roasting your own peppers take the trouble to also roast the tomatoes. You can do this in a very hot oven or over charcoal.
When the peppers and tomatoes are well blackened put into plastic sandwich bags and wrap in a kitchen towel until they're at least tepid. Remove the skins and seeds and roughly chop
Otherwise
Use a jar of roasted peppers and raw tomatoes and garlic
Put all the ingredients in a food processor and pulse to get the right consistency for you.