Prepare the avocados, onion, garlic, tomatoes, and cilantro according to the ingredients list.
Juice the lime into a large bowl. Using a fork or potato masher, mash the avocados in the bowl along with the lime juice. Season the mixture with the salt, cumin, and cayenne pepper.
Mix in the tomatoes, garlic, onion, and cilantro.
Cover and refrigerate at least one hour before serving.