FAIL: Creamy Tri-Pepper Dressing

I was actually really surprised this effort failed. When I rely on my own devices in the kitchen, I often end up with a meal that is mostly good but could use some tweaking or refining. That's okay, I expect that. But I made this from an ETL recipe online. Usually if I have a recipe, it's a no-fail, no-brainer. I expect for someone else to have ironed out the kinks. Which is why I was totally bummed to open up the fridge and see a cup full of what looks like chicken fat!
I suspect it was the soy milk. The recipe called for unsweetened soy milk. I only had light. That's the only thing that differs from the original recipe. I am determined to try again (and I'm honestly curious to find out where I made a mistake).