First, start by making a paste by adding the minced garlic, the juice of one lime, kosher salt, and cumin in a bowl. You will not have much, but really mix what you have really well. This step will help to make your ingredients work harder.
Next, mash all of the avocados until smooth with little chunks for good texture. When ready, add the paste and mix well to incorporate.
Finally, add the chopped serrano, and fresh cilantro. Mix and stir to combine.