Slow Cooker Brisket and Onions

1 tablespoon olive oil
1 1/2 pounds yellow or red onions (about 2 large onions), sliced into half moons
3 1/2 pounds beef brisket
Coarse kosher salt and freshly ground black pepper
6 cloves garlic, minced
2 cups beef broth
2 tablespoons Worcestershire sauce
1 tablespoon soy sauce (or tamari, if gluten-free)

See full recipe on: thekitchn