Recipe from www.thespunkycoconut.com. I posted it on here just in case the link should ever stop working for any reason. It's a great recipe and the best alternative I have found so far.
Cashew Sour Cream/Cream Cheese:
1 cup of cashews, soaked in water to soften 2-8 hrs, strain and rinse.
Add to the food processor of blender with:
1 to 2 tsp apple cider vinegar
3 to 4 tbsp lemon juice
1/4 cup water
1/4 tsp sea salt or Herbamare seasoning
Puree till creamy and smooth.
I like to add a pinch of onion powder to mine too. Yum.