Heat a skillet large enough to fit the roast on medium high heat for a minute
Add the non-dairy butter and allow to melt
Brown the roast on each visible side for 1-2 minutes
When complete, place the roast in the slow cooker, leaving the juices in the pan
Add the onions and red wine vinegar to the pan and saute for 1 min, stirring often
Add the onions, potatoes, and liquid ingredients to the slow cooker around the roast
Sprinkle half of the rosemary, garlic, salt, and pepper on the roast, and the rest on the surrounding ingredients
Cook on high for 4 hours, or low for 7-8, until meat is cooked thoroughly
Slice or shred roast to serve, and enjoy!