Prepare Tomatillos: Remove the husks before using, the husks are inedible. Tomatillos are very easy to cook with because they don't need to be peeled or seeded. Their texture is firm when raw, but soften when cooked.
Rinse before using as the tomatillo is covered by a sticky substance. Do not peel the green skin.
How To Prepare Chile Peppers:
Warning: Always wear gloves when working with hot chile peppers (fresh, dried or roasted chiles). Never touch your eyes when working with chiles. Gloves will protect your hands, but the capsaicin in the chile pepper sticks to all it touches, and if you touch near your eyes it will burn. Rinse well with copious amounts of water. Please do not learn this lesson the hard way!
Wash the chile pepper first.
There is no certain way to tell if a pepper is hot by looking at it, although I have heard many, many wife's tales about dark spots, cracks and anything else. But the only sure way to tell is by tasting.
Slice the chile pepper down the center with the tip of your knife.
You can see the membranes and seeds here in these two halves. The membranes are where the capsaicin is stored. It is this part of the chile pepper that carries the heat.
The seeds are not as hot, but since they are a part of the membrane they do have a slight bit more heat than the green outer chile pepper.
If you are simply dicing your chiles, the easiest way to clean them is to cut them into quarters. Then you can simply slide a sharp knife carefully down the green outer part of the chile pepper removing the white membrane and the seeds.
In a food processor, process prepared tomatillos, prepared chile peppers, garlic, and cilantro leaves until coarsely chopped.
Pour tomatillo mixture into a bowl and stir in olive oil, diced avocado, and minced onion. Add lime juice and salt to taste.
Enjoy with your favorite chips!