First dice your onion and put it in a medium to large saucepan with a little bit of Extra Virgin Olive Oil. Over a medium high heat let your onion sweat til tender then add your garlic, red pepper flakes, basil, and oregano. Let this get heated thru - you will be able to smell the herbs coming thru. Then add your tomatoes and your tomato sauce. Bring to boil then reduce heat.
Let this cook on a low heat while you are roasting your vegetables. Roast your poblano, bell, and jalapeno peppers til they have a good char on them. Then immediately put them in a glass container covering them with saran wrap to allow them to sweat and soften the charred skins. This only takes like 5-7 minutes. Then peel the charred skins off and discard those with the stems. Don't worry if you don't get all the little pieces off it won't hurt anything just get the majority of it off. Then make a slit in the side of them and lay them flat. Discard the stems and at this point you can either clean out the seeds and discard them or you can leave them in. This depends on how spicy you like it. (I like mine spicy so I left them in.) Dice them up and put them in the sauce pot with your tomatoes.
Let this mixture sit on a simmer for about 5 minutes or so then take an immersion blender and blend this mixture til smooth. It's ok if it leaves some chunks - any good tomato sauce has a few chunks in it - anyway, then you want to taste it and add salt if you think it needs it here. Then you can add browned meat here if you like or you can leave it without meat and pour over pasta and serve.