Tomatillos are the key ingredient in this recipe. Fresh and cooked they are used in Latin American green sauces. I found the Tomatillos and chicken combination very delicious! Slowly cooked, this chicken recipe has fresh new flavors that absolutely deserves to be discovered. The tomatillo is a small round fruit covered with a parchment-like, green husk. Fruit resembles a green cherry tomato and it's flavor is lemony and slightly acidic. Don't forget to remove the husks before using them.