Tomatillos are members of the nightshade family and are technically a fruit.  They come in varying shades of green to yellow-green and look like an unripe tomato wrapped in a paper husk.Tomatillos flavor is bright and acidic.  Their flesh is dense and less watery then a tomato.  The fruit has a sticky film on it, peel the husk and rinse with warm water.  

How to use the tomatillo:
Making a roasted tomatillo sauce or salsa that can be used or frozen is the most versatile.  Preheat the oven to 425 degrees.  Cut tomatillos and a couple of medium size onions in quarters and add 1 whole jalapeno (optional).  Add 4 cloves of garlic still in their paper jackets.  Toss with olive oil, salt and pepper, place on a sheet tray and roast until the onions, jalapeno and tomatillos have blistered some. Start checking at about 15 to 20 minutes.  Take out and cool.  Careful, there will be some hot liquid given off by the tomatillos.  Squeeze the garlic out of their jackets and transfer the cooled mixture to a blender and process until smooth.

Some ideas on how to use the roasted tomatillo salsa:
1) Stir into white chicken chili, posole,chicken tortilla soup at the very end of cooking.
2) Use as a sauce for baking chicken thighs or breasts.  The sauce will become more liquid but is wonderful to add shredded or sliced chicken into.  The chicken stays moist.  
3) Salsa to dip chips into.  
4) Stir into cooked rice.  Add lime juice and chopped cilantro.
5) Use as a dipper for garlicy, roasted potatoes.