Place the halved tomatoes on a rimmed baking sheet and drizzle with half the olive oil and sprinkle with salt and pepper. Roast for 30 minutes, until soft but still retaining their shape, then allow to cool,
While tomatoes are roasting, heat up the remaining olive oil in a medium skillet over medium-high heat. Sauté the onions and garlic, just a couple of minutes until translucent and tender. Set aside.
Once cooled, puree the roasted tomatoes, onion and garlic, the stock or both, and next 3 ingredients in processor until almost smooth. Salt and pepper, to taste.
Transfer to bowls, chill for 30 minutes to an hour, or up to 1 day, you can also serve room temperature or hot. Served with your favorite garnishes.
Notes
Roasting the tomatoes and sautéing the onions and garlic aren't necessary per se, you could definitely make this soup with fresh, raw tomatoes, onions and garlic, just the same. I just love the sweetness and depth of flavor, that roasting brings out. If you wish to strain the seeds from the tomatoes, you can puree the tomatoes with the stock first, alone, strain through a mesh strainer, then continue to puree with the other ingredients.You can also grill the tomatoes, to avoid the heat inside.