The Fed's QE3 has Brazil talking currency wars, and it's also pushing up commodity prices. This strategist sees a trade.

You can't really blame Brazil for disliking QE3. The country is trying hard to keep the real  in check, and falling interest rates in the U.S. make that harder, so it's not really surprising that the finance minister has threatened to impose a new tax on speculative foreign investment.

Boris Schlossberg, managing director at BK Asset Management, is looking at another effect of the stimulus move.

"The QE story is interesting because it is clearly flaming some price inflation amongst the commodities across the world," he told CNBC's Scott Wapner. And for Schlossberg, a currency maven, that suggests a trade.

Schlossberg notes that the Australian dollar "has been the darling of the currency market for a very long time" because the country's fortunes are so closely tied to China. But with China's economy slowing down, demand for the minerals Australia exports will likely slow as well.

At the same time, commodity price inflation will lift the value of New Zealand's exports of wheat and meat, and the New Zealand dollar "is going to benefit tremendously," Schlossberg says.

He wants to sell the Aussie against the kiwi just below current levels, at 1.2575, because that slippage would suggest the trade is starting to work. He recommends a stop at 1.2750 and an initial target of 1.2500. If the Aussie gets to that level, "see if we can squeeze it all the way down to 1.2000," Schlossberg says. He adds that the Reserve Bank of Australia could give the trade more juice if it cuts interest rates in October.

With rock bottom interest rates in the U.S., Europe, and Japan, "these are the kind of trades you need to be looking for, relative trades not absolute trades, because everything else in the currency markets looks kind of horrible," Schlossberg says.

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