My mother’s second concern was legit. Acorns in their raw state are full of tannins, which are toxic in high doses. To avoid death by dinner, the nuts must be rinsed with water until the compound is thoroughly leached out. Processing time varies depending on the type of oak you choose.

Steve Brill, who leads edible foraging tours of New York City parks and is known as Wildman, says acorns from white oaks are generally less astringent than those from red oaks. He advises avoiding the red variety altogether unless you have access to an unpolluted freshwater stream.

“The ideal process is to put acorns in a weighted sack and set them in the running water for a few weeks,” he said. “But only if you know there are no poachers around.”

Mr. Brill, who mills his own acorn flour from nuts collected in Central Park, alternatively suggests placing the sack in a toilet tank for a month. Each flush will provide a quick rinse. “The tank isn’t contaminated with sewage,” he said, “but be warned that the tannins will turn the toilet water brown.”

To date, his wife has refused to let him use this particular method.

I opted for something less unsavory by blitzing the acorns in a blender with some water and leaving them in a large, covered mixing bowl. The smaller pieces created more surface area, which in turn sped up tannin extraction. Without disturbing the acorn sediment, I replaced the tannic solution with fresh water every three hours until the nuts lost their bitterness.

My batch of white oak acorns took three days, but this could take up to three weeks depending on the nuts.

“It’s an art more than a science,” Mr. Brill said. “It’s safer to soak the acorns until the water is clear, but you can also just taste for sweetness.” In this case, trusting your palate is the secret to avoiding toxicity.