Preheat oven to 300 degrees F. To a baking sheet, add the halved roma tomatoes and halved hatch chiles. Sprinkle the tomatoes and chiles with salt and drizzle the tomatoes with one tablespoon for olive oil. Transfer to the oven to roast for about 1 hour, until they’re super juicy and a little shriveled up. Let them cool slightly on your kitchen counter.
To a small sauté pan, set over medium heat, add a tablespoon of olive oil. When warm, add the chopped onion and garlic cloves. Cook until softened about 5 minutes. Transfer to a blender.
Using a pair of tongs, add the roasted tomato and one of the hatch chiles (we’re gonna use the other hatch chile for the grilled cheese). You may need to do this in batches depending on the size of your blender. Pulse until smooth, about 1 minute. Pour the soup into medium pot, set over medium-low heat. Add about 1/4 cup of water to the blender (you can eyeball this) and swish it around to get all the leftover soup off the sides of the blender. And pour that water/soup mixture to the pot.
Bring to a gentle simmer for about 20 minutes, just so all of the flavors merry together. Give it a taste and add salt to taste. I added about 2 teaspoons.