When primary fermentation is complete, split 2 nice fresh vanilla beans lengthwise. Scrape out and reserve all the seeds and "gunk" in them. Cut the pods into roughly 2-3" pieces and add the pods, seeds and "gunk" to a secondary fermenter. Leave them there until you get the amount of vanilla flavor you like. I usually start tasting at about a week and a half, and may leave them in until 2 weeks. You may want to let them go a bit more than you think is necessary since the vanilla flavor fades with time. When the beer is done in secondary, rack to a keg or bottling bucket with about 375 ml. of bourbon. I use Jim Beam Black. You don't need to use an exceptionally good bourbon. The bourbon flavor should integrate with the porter and vanilla flavors, not stand out and shout "Bourbon!" You can determine the amount of bourbon for your own tastes through the following method....pour 4 2 oz. samples of the beer that goes into the bottling bucket or keg. Dose each with a measured amount of bourbon. Taste them to decide which you like best, then scale that amount up to your batch size. This beers does not need, nor benefit from, extensive aging. Generally, I prefer it within a couple months of brewing.