Mousse de Aguacate
I suppose it shouldn't come as any real surprise, since I'm a Mensan, that I am delighted by things in nature that deviate from the norm, such as the braided rings around Saturn or monotremes (the platypus and echidna: both mammals that lay eggs). The plant kingdom, in particular, seems to be replete with such "rule-breakers"—plants that are hard to define, difficult to predict, or that exhibit characteristics that differ from everything else in the category to which they belong.
One of these exceptional plants is the avocado. Fruit pretty universally produces sugars to some degree as part of the ripening process, but avocados produce oil instead. (They do produce some sugar while still on the tree, but sugar rapidly decreases once ripening begins.) While other fruit ripens best, and often ripens only, while still on the plant, avocados do not begin to ripen until they are cut off the tree. (The tree produces a hormone that keeps the fruit from ripening, and it is only when this hormone ceases to reach the fruit that ripening begins. Avocados can, in fact, be "stored" for months simply by leaving them on the tree.)
Avocado is the only fruit that cannot ripen anaerobically—if you keep it in a tightly wrapped plastic bag (like the one in which you brought it home from the grocery store), ripening stops. The fruit simply spoils when oxygen is reintroduced after having been denied for any significant amount of time. Also, chilling damages the fruit, not only while it's on the tree but also after it's picked. If you store your avocado in the refrigerator for very long, it will become discolored, and the flavor will deteriorate.
Avocados are native to the tropical Americas, from Mexico down to the top of South America. They are members of the laurel family of trees. Our word avocado is a modification of the Spanish aguacate, which comes from Nahautl ahuscatl or ahuacatl. (Also related is our word for that nifty avocado dip, descendant of a spicy Nahuatl sauce that the Spanish first called aguacamole.) Like most of the New World's contributions to the culinary scene, avocados have made the trip pretty much around the world, though they stick pretty universally to warmer climates, primarily Florida, California, the Mediterranean, Australia, South Africa, and a few Pacific Islands. Of course, they are still hugely popular in the region of their origin, appearing in everything from salads to sauces to ice creams.
In addition to being luxuriantly rich and delicious, avocados are wonderfully good for you. With 17 vitamins and minerals in all, they contain more potassium than bananas and also carry a substantial load of antioxidants. While they have a surprisingly high oil content, the oil is monounsaturated, which means it boosts your HDLs (the good cholesterol) and lowers your LDLs (the bad stuff). So eating avocados actually reduces your risk of heart disease.
The elegant and delicious mousse detailed below is indigenous to Cost Rica. I generally like to use a decorative mold when making this, to make it pretty for serving, but you can make it in a simple bowl. The amounts given below necessitate the use of a small mold (about 3-cups capacity). Most of my molds are six-cup capacity or larger, so I have to increase this recipe—but it doubles, and even triples, easily. (If you get to four or more avocados, you might want to use a food processor instead of a fork to create the mashed avocado mixture.)
There are a number of species of avocado that are regularly available. For this recipe, Hass avocados (the ones with the rough, leathery, dark green to black skin—the most common avocados sold in most of the U.S.), or similar California-grown varieties are your best bet. Using the larger, slightly waterier Florida avocado necessitates much adjustment of quantities in the recipe. They are delicious, but save them for stuffing with shrimp or crab salads.
Mousse de Aguacate
1 large, ripe avocado
1 small onion, grated
½ tsp. salt
¼ tsp. Worcestershire sauce
1 tablespoon powdered gelatin
¾ cup cold water
¼ cup boiling water
¼ cup whipped cream
¼ cup mayonnaise
Peel and pit the avocado and cut it into small pieces. Place avocado in a bowl along with the grated onion, salt, and Worcestershire sauce and mash together with a fork, blending until very smooth.
In a medium-size bowl, soften the gelatin in ¼ cup of the cold water. Add boiling water and stir until gelatin is dissolved. Then stir in the remaining ½ cup of cold water and cool. When gelatin mixture is the consistency of raw egg whites, gradually fold in the whipped cream, mayonnaise, and mashed avocado mixture. Pout into a mod that has been rinsed with cold water. Refrigerate until set, preferably for at least 24 hours. To serve, garnish with tomato slices and lettuce leaves.