2 pounds beef chuck, blade steak, roast, or stewing beef
3 cloves garlic
2 medium green onions
1/2 cup beef stock
1/4 cup low-sodium soy sauce
1/4 cup packed brown sugar
1 1/2 tablespoons rice wine vinegar
3 teaspoons gochujang
2 teaspoons grated fresh ginger
1/2 teaspoon freshly ground black pepper
3 tablespoons water
2 1/2 tablespoons cornstarch
2 teaspoons sesame seeds (for garnish)