Quick Black Bean Tostadas

Name: Quick Black Bean Tostadas
Cuisine: Mexican, Latin American, American
Ingredients: 10 6-inch corn tortillas; 2 15-oz. cans black beans, rinsed and drained; 2 tablespoons lemon juice; 1½ tablespoons onion powder; 1½ tablespoons garlic powder; 1 teaspoon ground cumin; Sea salt, to taste; Freshly ground black pepper, to taste; 2 cups finely shredded romaine lettuce; 1 green onion, thinly sliced (¾ cup); 1 medium tomato, finely chopped (½ cup); 3 tablespoons fresh cilantro, finely snipped