Doing so was supposed to result in cupcakes with smooth, perfect-looking tops as they did in sea-level. Instead, my results were cupcakes that still had wrinkly old-man tops. Not as wrinkly and bloated as the unaltered recipe (see the picture below, which shows the results from the original, unaltered Hummingbird Bakery Cookbook recipe), but definitely not that great of an improvement.
The taste of this second attempt was also much worse. My hypothesis that I had to reduce the vinegar in equal proportions to the baking soda (I feared for vinegar-tasting red velvet cupcakes) was flat out wrong. My cupcakes were significantly drier in texture, with a flavor that was dull and flat. No wonder high-altitude sources like King Arthur Flour Company's high-altitude baking guide or Pie in the Sky only suggested altering baking soda quantities and nothing else!
So this time around, I decided to follow exactly what the guides told me. I would leave the recipe's vinegar quantity alone and only alter the quantity of baking soda (in bold):
- 4 tablespoons unsalted butter, at room temperature
- 3/4 cup sugar
- 1 egg
- 1 tablespoon unsweetened cocoa powder
- 2 tablespoons red food coloring
- 1/2 teaspoon pure vanilla extract
- 1/2 cup buttermilk
- 1 cup plus 2 tablespoons all-purpose flour
- 1/2 teaspoon salt
- 1/4 teaspoon baking soda (reduced from original amount of 1/2 teaspoon)
- 1 1/2 teaspoons distilled white vinegar
They look significantly more like Hummingbird red velvet cupcakes when baked at sea-level, so there's that. Smoother tops that bounce back when touched. No bloating or over-expanding over the cupcake case.
But more importantly, how did they taste?
... not great.
The cake's texture was too heavy, dense, and chewy. One of my favorite things about red velvet cake is its texture -- heavier than your normal sponge cake, but still light enough to be considered fluffy. This was definitely not fluffy or light. It didn't taste bad, mind you -- the texture was just off. Way off.
Maybe it's time to accept defeat and admit that the original Hummingbird Bakery recipe for red velvet cupcakes works perfectly fine at high-altitude?