Tomatillos belong to the same plant family as tomatoes but remain green when ripe and have a thin husk. They were a staple of Aztec and Mayan cooking and continue as a common ingredient in Mexico and Guatemala today.
Once ripe, tomatillos can be stored in the fridge for up to two weeks. If picked before fully ripe, they last as long without refrigeration.
Tomatillos normally found in stores are harvested early when the fruit has a light sour taste, which is ideal for the making of green sauces. (However, the fruit becomes sweeter when picked later and can then be used as a tomato substitute.) Remove the husk, rinse the skin, and boil with onions, cilantro, garlic, peppers, and spices into soft. Then puree for salsa verde, a smooth-textured sauce as spicy as the amount of peppers you added to the mix!