Preheat the oven to 450° F.
Lightly grease a baking sheet with coconut oil.
Lightly grease a baking sheet with coconut oil. Cut the tomatoes in half lengthwise and cut out the very tips of the cores. Place, cut side down, on the prepared baking sheet. Brush the tomatoes with a little bit of oil and sprinkle their backs with the garlic powder, salt, basil, oregano, and pepper.
Bake for 20 minutes. Let cool.
While the tomatoes are roasting, heat a tablespoon of the coconut oil in a skillet over medium heat. When hot, add the onion and mushrooms and sauté for 10 to 15 minutes.
Scrape the tomatoes from the baking sheet into a blender. Blend at medium speed until smooth.
To the skillet holding the mushroom mixture, add the vegetable stock, tomato paste, and blended tomatoes. Bring to a boil and then remove from the heat.
Add the milk and make sure the soup is heated through. Serve hot and sprinkle with chives.
A serving is about 1 ½ cups.