Trim excess fat from roast; combine dry soup mix and onion on a sheet of aluminum foil or wax paper.
Roll roast in mixture to coat well.
Place coated roast in a crockpot, pour wine or water over; cover.
Cook on medium for 8 hours, turning after 4 hours, if possible, or on high for 4 hours, turning after 2 hours if possible, or until meat is tender.
Serve with mashed potatoes and buttered green beans.