- Cut the avocados in half and remove the pit.
- Using a spoon, remove the flesh from the skin.
- Place the red onion, serrano chile and cilantro in a molcajete and mash them. (A molcajete is a traditional Mexican mortar and pestle made of volcanic rock. If you don’t have a molcajete you can use a fork to mash.)
- Add the avocado and fold it in. Add the tomatillos.
- Place the guacamole in a serving dish and top with the cheese.
- Serve with lime wedges and totopos (fried tortilla chips).