Beef Brisket Sandwich

Name: Beef Brisket Sandwich
Ingredients: 2 tablespoons olive oil; 1 2½-pound beef brisket, trimmed and cut into 2 pieces; Kosher salt and black pepper; 1 onion, chopped; 1 1/2 cups ketchup; 1 tablespoon Worcestershire sauce; 1/4 cup light brown sugar; 3 tablespoons apple cider vinegar; 1/2 cup plain Greek yogurt; 4 teaspoons dill pickle juice, plus sliced pickles, for serving; 1/2 head napa cabbage, shredded; 2 scallions, thinly sliced; 2 carrots, shredded; 8 slices thick bread (such as Texas toast), toasted