Preheat your oven to 180 deg C. Place the tomatoes and capsicum in a baking dish. Sprinkle with olive oil, balsamic vinegar, garlic and salt and pepper. Roast for about 45 mins or until tender. You should notice that the tomatoes and capsicums are all "wilted" and soft.
At about the halfway mark of the vegies roasting, add some olive oil to a pan and fry the chilli. Add the stock, the potatoes and the tomato paste. Bring to the boil and then lower the heat to medium. Cook for about 10 mins or until the potatoes are tender. Once cooked remove the pot off the heat and set aside.
Your tomatoes and capsicums should be ready about now. Remove from the oven and add them to the potato mixture. Make sure you scrape the pan down. We want every single bit of that roasted goodness! Add the basil leaves as well.
Using one of those nifty stab blenders, blend until everything is smooth. You may prefer a "chunkier" texture, so just blend less.