Grilled Butternut Tostada - Rick Bayless

Ingredients

• 1 small (2 pound) butternut squash
• 1 large red onion, sliced into ½-inch thick rounds
• Vegetable or olive oil
• Salt and black pepper, preferably freshly ground
• 1/2 of a 15-ounce can black beans, drained OR a generous ½ cup home cooked black beans
• 12 tostadas, store bought or homemade
• 1/4 cup finely crumbled Mexican queso aňejo or other garnishing cheese such as Romano or Parmesan
• About 1 cup salsa for serving (I think Chipotle Salsa is especially delicious here)