Black Bean Burger

Name: Black Bean Burger
Ingredients: 2 cups black beans, drained and mashed with a fork; 1 cup seasoned breadcrumbs; 1/4 cup grated onions; 1/2 teaspoon chili powder; 1 egg; Salt and freshly ground black pepper; Canola oil, for oiling grill pan; 1 to 2 kaiser rolls; Arugula, for serving; Sliced tomatoes, for serving; Mayonnaise, for serving