The culinary scene – and greater citizen population, really – of Denver, appears to be split on the city’s complicated relationship to Rocky Mountain oysters. It seems impossible to get any consensus on whether the dish is a local delicacy or a novelty dish hanging from the city’s neck like the deep-fried genitals of an albatross.
You see, these oysters aren’t bivalves in the manner that mussels, clams or other sea life might be recognized. The most popular – or at least most infamous – oysters in Colorado are harvested from the scrotums of bulls. Rocky Mountain oysters are bull testicles.
Sorry to be explicit, but I’ve had to spell out to more than one new-to-the-city local what the oysters on scattershot gastropub menus across town actually are. The responses ranged from incredulous to comical, with a lot of head-cocking thrown in for good measure. “Seriously?” was a common refrain. Seriously.
Rocky Mountain oysters, which also go by other names like prairie oysters, mountain tenders, calf fries and cowboy caviar, date back to the rancher explosion resulting from expansion into the American and Canadian West. As farmers settled in what is now the central and western United States, they found themselves living in remote areas that wouldn’t see railroad supply chains built for decades. Cattle ranching and farming were necessary ways of life on the frontier.
Perhaps inspired by the Native American mythology about using every part of a slaughtered buffalo, or perhaps just because they had few other options, impoverished settlers began incorporating the testicles of newly castrated bulls into their diets. It’s not that ranch hands necessarily sought the organs out as the missing ingredient in a holiday feast. The removal of the testes was already happening, typically in the youth of the calf.
Castration reduces aggression in males who might otherwise be hormonally driven to fight amongst themselves for the right to mate with a ranch’s females. Castration before a bull reaches sexual maturity also results in some beneficial physiological results, which fundamentally influences the growth of skeletal muscle as the animal ages. So pairs of perfectly edible, protein-rich beef organs were the byproduct of an already established practice of animal husbandry.
The decision to therefore eat the curious meat wasn’t a difficult one to make. After the removal of various tissues and membranes, ranchers grilled their newfound “oysters” on open coals or wood fires. A single raw bull testicle contains about 26 grams of protein and very little fat. Plus, testicles are naturally rich in zinc, an immune-system booster scarcely found in frontier diets before the advent of year-round citrus in grocery stores.
The dish was hardly viewed as off-putting or unsavory, and the relative rarity of testicles, owing to the seasonal harvesting of new bulls, created a reputation around the food akin to that of a delicacy.
Bull testicles are still eaten today across mountainous states like Colorado and Montana, as well as parts of Canada, where they now appear on menus under a host of whimsical, tongue-in-cheek names. Food festivals dedicated to their consumption are a summertime staple in old frontier towns and major cities alike. Though, it should be noted that Montana’s world-famous Testicle Festival called it quits in 2018 after 35 years of oyster consumption.
In festival food booths and commercial kitchens alike, Rocky Mountain oysters are prepared in almost limitlessly versatile ways. Deep-fried oysters are served topped with ironic dollops of cocktail sauce across Denver pubs. Paillards are dusted with spices and sautéed after being pounded flat. Rocky Mountain oysters are poached, broiled, baked and ground. In fact, you can prepare them just about any way whatsoever that you might like.
So are they a regional delicacy or a stomach-curdling novelty that has long stopped being funny? The question is almost beside the point. A single festival dedicated to the bivalve impersonators can go through 50,000 pounds of bull testicles in a single weekend. Whether you love them or loathe them, people are certainly gobbling them up. And that’s no bull.