Instructions

1. Preheat the oven to 425F. Line a baking sheet with foil.
2. In a medium bowl, whisk together 2 tablespoons of the vegetable oil, 2 teaspoons of the chili powder and chipotle chili powder. Season with salt and pepper. Add in the tomatoes and onion and stir to coat. Arrange on the baking sheet in a single layer. Roast, stirring once, until tender, about 25 minutes.
3. Meanwhile, place the spaghetti squash, cut side up, in a microwave safe dish. Add about 1/2 cup of water, then cover the dish with plastic wrap and microwave until tender, 10-15 minutes. Let sit until cool enough to handle, then using a fork, gently scrape the flesh into a bowl.
4. In a skillet, heat the remaining tablespoon of vegetable oil over medium heat. Add the beans and cook until heated, mashing as they warm up.
5. Spread the beans on the tostadas. Top with some of the spaghetti squash, some of the vegetables, and a dollop of sour cream. Top with fresh cilantro and squeeze lime juice over the top before serving.