This was our first try at roast, and everyone voted it a home run first try. If your roast is larger or smaller adjust the amounts of seasoning accordingly.
Layer the onion in the bottom of a crock pot.
Brown roast on all sides (about 3 minutes a side) and then place in crockpot.
Combine all of the dry herbs and salt. Sprinkle over roast. Lay the fresh sprigs of herb on top of the roast.
Drizzle the balsamic vinegar over all and cook on low until the roast is tender and flakes when prodded with a fork. This usually takes 6-8 hours in my crockpot.