Preheat oven to 450 degrees.
Place halved and seeded peppers, garlic cloves (do not peel), tomatillos and onion quarters onto baking sheet lined with tin foil. Roast in the oven for 45 minutes or until pepper skins are blackened.
Place in air tight container to cool. Once cooled enough to handle, peel tough skin off.
Squeeze garlic cloves out of their skin. Put all peeled and roasted vegetables in the blender and puree.
Pour blended mixture into a large pot.
Add chicken stock, cumin, sugar, salt and pepper to pot and simmer for 15 to 20 minutes. Turn heat off and add fresh chopped cilantro.
Use your preferred canning method to can.
Or store in the refrigerator until ready to use. Keeps in the fridge up to one week.