Preheat the broiler with an oven rack about 4-5 inches from the heating element. Line a sheet pan with tin foil and roast the tomatillos, hatch chile, and the tomato under the broiler until they are blackened in spots, about 5 minutes. Flip the vegetables over and roast the other side for another 3-5 minutes.
In a blender combine the roasted tomatillos, tomato, and their juices. Remove the stem from the hatch chile and peel the loosened skin from the flesh then add the pepper to the blender. Add the onion,flesh of the avocado, lime juice, garlic, cilantro and salt to taste