Slice the avocados in half, peel and discard the pits. Place the avocado meat in a large mixing bowl. With a fork, gently mash the avocados leaving the mixture a little chunky.
Add the garlic, salt, cumin, cayenne, onion, tomatoes, Serrano pepper, cilantro and half of the lime juice. Combine gently and move the whole mixture to one side of the bowl you’re working in.
Pour the remainder of the lime juice on top (to help seal in the fresh bright green color from the avocado).
Cover the guacamole directly with saran wrap so that none of the surface is exposed to the air. This also helps retain the bright green color.
Refrigerate for 1 hour.
Taste the guacamole and season accordingly. As the guacamole sits, it marinates and gets spicier and limier. That’s why I let it sit for an hour before tweaking. If it just isn’t quite right, add salt.
Serve and enjoy!