How to Make It
Light a grill or preheat a grill pan. Brush or drizzle the bread with olive oil and grill over moderate heat, turning once, until lightly charred, 1 to 2 minutes total. Transfer to a work surface to cool slightly, then cut each slice into thirds.
In a medium bowl, mix the olives with the vinegar, chiles and the 1/4 cup plus 2 tablespoons of olive oil; season lightly with salt and gently mix in the beans. Spoon the bean-and-olive topping on the crostini, garnish with mint and serve.