I recently tried an unfiltered IPA that was fantastic! I'm a newbie homebrewer and would like to take a shot at one. What makes an IPA unfiltered? Can I take any IPA recipe and modify it to be unfiltered?
As a homebrewer, pretty much all of your beers will be "unfiltered". You can take steps to make them even more unfiltered, but pretty much, you'll always be there.
Most production breweries filter their beers through a variety of methods. When they make an unfiltered beer, they just skip those steps. The result is often a grainier beer, something with more actual body, as their are leftover grain hulls, hop flecks, and groupings of yeast floating about.
If you find your beer at home is too clear and you want more of the unfiltered profile, try adding a little bit of flaked wheat to your recipe.
What makes a beer unfiltered is that there is no filter applied to the finish product prior to packaging process. I know that may seem obvious, but I point it out to emphasis that if you are expecting some sort of recipe difference, you probably won't find one.
The filtering process arguably strips beer of some elements such as colors, flavors and aromas. Key to the IPA question is hop aroma and flavor. Many times this can simply be overcome at the recipe end while continuing to use a filter for shelf stability and clarity issues.
That said, when you homebrew you are making unfiltered beer... as long as you aren't employing some sort of filter. Your beer should be a fairly straight representation of unfiltered commercial beers. If you aren't getting the right flavor in comparison to some of your favorite commercial examples, I wouldn't be concerned with the unfiltered nature of it. I would focus on your process and your recipe more.
IPAs tend to be cloudier when dry-hopped, particularly if you dry hop with pellets. I brewed an IPA where I did no dry hop, but rather made a hop tea in a French press where I steeped what would be my bittering hop pellets in a pint of the not-yet-boiling wort after lautering. When I hit a boil, I pressed the tea off the hops, decanted it into a container and set it aside until the boil was done. I added it at flameout. I believe this contributed a good bit of that typical IPA haziness to the finished beer.