1. Heat oil
in Dutch oven or deep 12-inch skillet over medium heat until hot.
Place beef brisket in Dutch oven; brown evenly. Remove brisket
from Dutch oven; pour off drippings.
2. Add onions
to Dutch oven; cook and stir 3 minutes or until crisp-tender.
Return brisket to Dutch oven place on a rack about 1 inch above
the bottom. Add broth or beer; bring to a boil. Reduce heat; cover
tightly and simmer 3 to 3-1/2 hours or until brisket is fork-tender.
Remove brisket; keep warm.
3. Cook cooking
liquid over medium-high heat 5 minutes or until reduced by half.
Stir in horseradish.
4. Meanwhile
trim fat from brisket; carve diagonally across the grain into
thin slices. Serve with sauce.