The phrase "an unusual method of" is correct and usable in written English.
You can use it when describing a method or approach that is not commonly used or is different from the norm.
Example: "The researcher employed an unusual method of data collection that involved participant observation in a virtual environment."
Alternatives: "a unique approach to" or "an atypical technique for".
An interesting species of the genus Miastor exhibits an unusual method of reproduction called paedogenesis: large larvae produce smaller daughter larvae that remain inside the mother larva, feeding on it and eventually consuming it.
Ginkgos have an unusual method of reproduction.
And although there are now a few more fractional opportunities in Paris, it is still an unusual method of ownership.
But by 1 May, some wondered whether it could come sooner, perhaps via an unusual method of delivery.
He said that holding a press conference the day before the release of the autopsy report was "an unusual method of releasing information.
One Golisano charge, that New York has lost 300,000 jobs under Mr. Pataki, employed an unusual method of counting job loss.
The nearby De Morgenzon estate in Stellenbosch likewise employs an unusual method to get the best out of its grapes - they play music to their vines through strategically placed speakers.
Balthazar Birdsong employs an unusual method: instead of using flashcards and a metaphorical whip, he sends Norman off to read the Ingmeister's Third New International Dictionary, Unabridged, starting with A and ending with Z, at which point (at least theoretically), Norman ought to be fully prepped for next year's admissions test and, it would seem, for life.
The Civilians make charmingly straightforward musical theatre about subjects both mundane (lost ephemera, in "Gone Missing") and controversial (evangelical Christianity, in "This Beautiful City"), using an unusual method: its members interview scores of people, and weave their responses, often verbatim, into a show.
Heather Lindstrom has a somewhat unusual method of managing tense situations on the softball mound.
That's why, after seven years in love and no wedding date on the calendar, the two 27-year-olds opted for a new, rather unusual, method of celebrating one of society's oldest institutions: with an online fundraising campaign via the website GoFundMe.
