Unfold the brisket and cut into two equal pieces that will fit in your saute skillet or cast iron pan. Coat the skillet with oil and heat over medium-high heat. Salt and pepper the brisket. Sear until a golden brown crust appears on both sides of the meat. Remove and place in your slow cooker insert.
Add a little more oil to the pan and heat over low-medium heat. Slice the onions into thin half moons and saute gently until they are soft and lightly caramelized. Add the minced garlic and cook until tender and fragrant. Add to the slow cooker insert, tucking under and around the meat.
Heat the broth to boiling and stir in the two sauces. Taste and adjust seasonings. Pour over the meat.
Cover and cook in the slow cooker on low heat for 6-8 hours or until the brisket falls apart. Or you may cook on high for 5 hours if you need it to be ready sooner, but the brisket could be slightly tougher as a result of faster cooking.