Slow-Cooker Pot Roast with Root Vegetables and Red Wine

3 Tbs. minced garlic

1/4 cup plus 1 Tbs. tomato paste

1 tsp. dried sage

1 3-1/2-lb. boneless beef chuck roast

2 tsp. kosher salt

10 grinds black pepper

2 Tbs. unsalted butter

1-1/2 cups finely chopped Spanish onions

3/4 cup finely chopped celery

3/4 cup peeled and finely chopped carrots

3/4 cup peeled and finely chopped parsnips

1/4 cup all-purpose flour

1 cup red wine, such as Pinot Noir

1 14-oz. can whole peeled tomatoes, with juice

1/4 cup low-sodium chicken stock

1 Tbs. honey

4 sprigs fresh rosemary, tied together with kitchen twine

cooked polenta, for serving