In a large bowl, add the tomatoes, garlic, onion,red pepper and potato. Drizzle with olive oil and sprinkle with salt and pepper. Stir to coat. Transfer the vegetables to a large baking pan with raised edges. Spread into a single layer, tomato cut sides down. Roast on center rack of oven for 25 - 30 minutes, until tomatoes begin to char on top.
Scrape the contents of the baking pan, including juices, into a large pot. Stir in the broth, tomato paste, dried basil (if using instead of fresh basil) and parsley.
Bring the pot to a boil, then reduce heat to simmer for 15 - 20 minutes. The potatoes should be fork tender. Add fresh basil during the last 5 minutes of simmering to soften.
In the pot, blend the soup with an immersion blender until smooth.
Chef Tips
I used approximately 2 pounds Beefsteak, 1 pound Roma and 1 pound cherry tomatoes.If salt sensitive - omit the measured salt and only salt to taste