Place peeled and washed tomatillos in a pot. Cover with water. Bring to a boil, reduce to a simmer and cook for 10 minutes. Using a slotted spoon, add the tomatillos to the blender along with 1/4 cup of cooking water. Add in the jalapenos, onion, garlic, cilantro and salt to taste. Pulse to blend until as smooth as you like it.