If using canned tomatillos, drain and place in the blender. If using fresh tomatillos, remove the skin and place the tomatillos and jalapeno on a pan. Broil for 5 minutes. Flip and broil 3-5 more minutes, or until dark spots have appeared. Alternatively you can boil tomatillos in a pot of water for 5-10 minutes. Place on a paper towel to dry and allow to cool.
Allow the tomatillos to cool and then place the cilantro, lime juice, sugar, garlic and jalapeno in a blender. Add tomatillos and blend until the salsa is smooth. Salt to taste. Add more jalapeno if you like it spicier. Add more sugar if you like it sweeter.
Refrigerate salsa verde at least 1 hour before serving. Enjoy with fresh tortilla chips.