Slice the red bell peppers, tomatoes and onion in half. Remove the seeds and stems from the bell peppers, the stems from the tomatoes and the outer peel from the onion. Then, place these all on a baking tray and drizzle the veggies with olive oil and season with salt and pepper. Use your fingers to rub the oil and seasoning on both sides of the veggies.
Roast the veggies for 25-30 minutes, or until the top side is charred black.
Use tongs to transfer the bell pepper to a glass bowl and cover with plastic wrap for about 20 minutes, to steam the bell pepper.
When the other veggies are cool enough to handle, remove their skins and transfer to your Vitamix or high-powered blender. You should be able to easily squeeze out the garlic cloves from their skin as well.
Add the tomato paste, balsamic vinegar, dried basil and water (or stock) to your blender. Blend everything on high until smooth.
At this stage, the soup will be warm. If you'd like it hotter, blend for 4-5 minutes. The friction of the Vitamix blades will heat it up.
Before serving, top with optional garnish.
On an early recipe attempt, I added fresh basil to the soup before blending, but it turned the soup a murky brown color. So I recommend dried basil rather than fresh basil in the soup. But you can use fresh basil to garnish.
I also used an opaque vegetable stock on one attempt and it changed the color of the soup as well. If you prefer using stock, I recommend using one that is fairly clear in color.
If you want to skip the roasting step, you could definitely used jarred roasted red peppers and canned tomatoes. Though I'd recommend dicing the onion and quickly sautéing with the garlic (mince it) in a little olive oil, to keep the flavor profile similar.This soup makes for great meal prep. Just blend it up and freeze.