1.5 cups balsamic vinegar
2 tablespoons canola oil
1 small Spanish onion, coarsely chopped
1 lg. cloves garlic, coarsely chopped
.5 cup ketchup
1 tablespoons ancho chili powder
1.5 tsp paprika
2 tsp Dijon mustard
1.5 tsp red wine vinegar
1.5 tsp Worcestershire sauce
1 small chipotle chile in adobo, chopped
1.5 tsp dark brown sugar
2 tsp honey
2 tsp molasses
Pinch salt and freshly ground black pepper, plus more for seasoning
1 (2-pound) flank steak

1 French baguette, sliced
Olive oil
Salt and freshly ground black pepper
1 cup grated Monterey jack cheese
Sliced scallions, for garnish