From an earlier post on page 2 in this thread:
The Jalapeno puree is made by roasting jalapenos in the oven at ~250 and then blending them up with a small amount of water and then put the blend through a strainer. For a 5.5 gallon batch I'd recommend using 6 to 7 jalapenos (the 8.00 oz on the recipe is just an estimate, not exact).
I just drank the last bottle of this that we bottled on 2/5/14 on Monday, April 21st. I must say, this stuff definitely gets better with age! The spiciness of the jalapenos drops out quite a bit, but it's definitely still there. I hadn't had a bottle in a while, and finally decided to bust out the last bottle and give it a try. I'm now planning on making a 10 gallon batch with a friend on the 10th of may. Cheers!