Peel and thoroughly wash tomatillos until not sticky to touch. Place a skillet over medium-high heat and heat for 1 minute.
Add the tomatillos, tomatoes, garlic, and chile to the dry pan. Once chiles have softened, remove them from the pan and set them aside. Remove the garlic cloves and place them with chiles. Let the remaining ingredients char for an additional 8-10 minutes, turning to get as much char as possible. Place charred ingredients into a small pot and add one cup of water. Bring to simmer and remove from the heat. Place tomatillos, tomatoes, chiles, and garlic into a high-speed blender. Add 1/2 cup of water, and blend until well combined, adding more water as needed to create desired consistency.
In a medium-sized bowl, add the diced onion and chopped cilantro. Pour the chile sauce over the cilantro and onion. Mix until well combined. Add the juice from the limes and the salt. Mix well. Cover and chill for at least 1 hour. Enjoy!