I noticed this use of the verb relish on a cooking site:
I was happy to find the recipe again at Sweet Little Bluebird so I could relish in my childhood memories.
In current use, the verb relish is transitive. It takes an object. One might relish childhood memories, but one does not relish in them. I think the writer was confusing the verb relish with the verb revel.
Apparently other English speakers also use relish in this way, chiefly in the context of recalling pleasurable memories, but in other contexts as well. Here are a few examples, not all of them from nonprofessional writers:
Bernard paused, letting me relish in the memory that wasn’t very long ago at all.—Published novel.
While this is a sad time for the organization, we all can relish in the memory of helping so many dogs over the years.—Nonprofit site.
There’s no time for Pirates to relish in accomplishments.—Pittsburgh Post-Gazette.
But, for now, consumer advocates and victims of pharmaceutical drug companies can relish in this victory and rest assured that they have preserved their right to hold pharmaceutical companies accountable in court.—Law Dragon.
The etymology of relish is cloudy. Its literal use, both as a verb and as a noun, has always been in the context of tasting and eating. Figuratively, the verb means “to take pleasure or delight in; to enjoy greatly.”
Here are examples of correct usage of relish:
Start your day with Blueberry Cornmeal Pancakes and then, for dinner, invite guests over to relish a batch of Four Bean and Sweet Potato Chili with Skillet Corn Bread.
Winners must learn to relish change with the same enthusiasm and energy that we have resisted it in the past.—Tom Peters.
Think big thoughts but relish small pleasures.—H. Jackson Brown, Jr.
The verb revel also has to do with enjoyment and pleasure.
The earliest meaning of revel was “to be festive in a riotous or noisy manner.” In modern usage, to revel means, “to take great or intense delight or satisfaction in.” Unlike relish, revel is properly followed by the preposition in:
Summer is a time to revel in reading.
July 4 is a time to revel in hard-earned liberties.
If you want to revel in BHP’s share price, don’t look beneath the surface.
Barcelona stars revel in Champions League victory.
Any relaxation in the strict anonymity rules…would only allow young offenders to revel in their criminal status.
Both relish and revel connote enjoyment, but relish takes a direct object, and revel is followed by in.
Another difference between relish and revel, though a subtle one, is that revel implies enjoying something for a longer period of time than relish. When you relish something, your enjoyment is intense but brief; the time it would take to eat a hot dog, for example.