I happened to catch an episode of Good Eats a few days ago. He did a Peaburger recipe I thought looked good. I tried it last night, and it got good reviews from the family, so I will be using this recipe again.
I used yellow split peas and chopped portabella mushrooms, because that is what I had. It has some time-consuming steps, I modified the recipe for using a pressure cooker to speed thing up. I also replaced pulsing it in a food processor after cooking with just mashing it a little by hand.
The recipe is on this web site, if anyone is interested:
http://www.goodeatsfanpage.com/Season9/peas/peas.htm