Take however many tomatillos you have or want to use. Cut them in half, and put the cut side down on a baking pan.

Then add aromatics, again, in the amounts you want. (A good place to begin is about one quarter the amount of jalapeno in bulk as you have tomatillo - but vary by taste.) Add onion and garlic if desired. Again, cut them in two (seeding the jalapenos) and put them cut side down on the pan.

Broil for 7-10 minutes, until softened and starting to bubble and char just slightly. Let cool.

Scrape everything from the pan, including the liquid from the tomatillos, into a food processor. Puree.