One method for getting a good guinness clone is to open a can of the storebought stuff, and pour it into a pot and let it sit out until it goes sour - usually about the time it takes to make a full batch of you stout recipe there (which is almost identical to my house stout, and turns out awesome.) Then once the beer is finished fermenting, add small amounts of the soured guinness until the entire batch has that tang, then carb and serve.
I've had excellent results using Northern Brewer hops exclusively in my stout recipes to nail that minty taste that Murphy's seems to have. Works a treat guv'
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