Science Tidbit: Avocado flesh turns brown once exposed to air because of the enzyme polyphenol oxidase (PPO), which causes the reaction of polyphenols in the fruit with oxygen in the environment, prompting the formation of quinones and secondary compounds, and causing darkening of the exposed tissue; this is called enzymatic browning . Several conditions may inhibit enzymatic browning, besides physical barriers (covering): lowering temperature (that is why refrigerated guacamole stays greener longer); lowering pH (that is why adding lime juice is recommended); blanching to denature the enzyme PPO (I actually found this advice, which I must try soon: heat treat the avocados before slicing! ); and not something for the kitchen: genetically modified varieties that suppress the extraction of PPO (is it just me, or avocados are not as fragile as they used to be?)
I know I am going to date myself by making this comment, but when I first came to Canada, avocados were very expensive and many people did not know how to eat them. It was actually thanks to the popularity of California sushi rolls that the demand for avocados became great enough to justify having them as a regular offering at supermarkets, and the price went down as the quality went up. Fast forward to present time, and not only sushi and avocados are still popular, but guacamole has become a well-known topping for anything from burritos and nachos, to even hamburgers! And there are so many ways to prepare it, one has to wonder which recipe is the real deal. As I have mentioned before, the word guacamole derives from Nahuatl and it simply means “avocado sauce”; the Mexica (Aztec) had avocados, tomatoes, tomatillos, hot peppers, and even some sort of small onions, but garlic, cilantro, and limes were not known in the New World before the arrival of the Spaniards, so the origin recipe was probably very simple. I rarely buy prepared guacamole, because most commercial recipes include garlic which, I declare, does not belong in guacamole. It is therefore wonderful that avocados are now readily available, because it is very easy to slice and prepare them fresh, and follow the guacamole recipe that suits my preferences and my family’s.
I only have access to two varieties of avocado around here: Caribbean, which is large, round and green, with a glossy skin and a mild, even a little sweet taste; and Hass, the elongated avocados, with a dark and textured exterior, that are creamy and bright green inside. The Caribbean are probably great in smoothies and desserts, but for guacamole, Hass is the way to go.
I started by preparing batches of mashed and cubed avocado, and from there, I could mix and match with basic ingredients and other sauces, to build three different versions of guacamole: simple, classic and green. I sliced the avocados lengthwise with a paring knife, going around the pit. I removed the pit applying the Mexican way: you rest the halved avocado on a cutting board and hit the pit with the blade of a kitchen knife, as if it were an axe; pick up the avocado and separate the pit by lifting the knife; set the avocado half aside and very carefully, hold the pit by wrapping it with a paper towel, and shake the knife to pull it out of the pit. It is not necessary to use this method if the avocado flesh is going to be mashed, but for nice cubic pieces, the pit has to be removed without damaging the flesh.
I chose the best halves for cubes; I scored a grid on the avocado halves, squeezed the peel very gently to loosen up the pieces, and also gently scooped them onto a bowl with the tip of the knife. In a separate bowl, I prepared the rest of the avocado by scooping the flesh and mashing it with a fork.
Now I have two presentations for my avocados, to start preparing the guacamole
For the simple guacamole, I took one portion of the mashed avocado and seasoned it with chopped hot green peppers, salt and lime juice
For the classic guacamole, I used the rest of the mashed avocado and mixed it with an equal amount of pico de gallo salsa
For the green guacamole (also called “green sauce with avocado”), I used the neatly cubed avocado and dumped it softly on top of a batch of cooked green sauce.
I stopped at that point, but it is easy to imagine all the possible permutations and combinations with green raw sauce, more than one sauce, spices, …