In a small skillet, heat the remaining 1 teaspoon oil over medium heat. Add the onion and sauté for 4 minutes or until softened. Add the garlic, cumin and oregano, and cook, stirring, for another minute, or until fragrant. Transfer the onion mixture to a medium bowl and add the beans. Mash with a fork until well combined and slightly creamy. (If you prefer a smooth texture, pulse a few times in a food processor.) If the consistency is too stiff to dip a chip in, add a tablespoon or two of the reserved bean liquid.
Spread the mixture onto the bottom of a (1-quart) shallow edged serving dish.
In a small bowl, combine the diced avocado with the salsa and spread over the bean mixture.
In another small bowl, combine the sour cream with chipotle and lime juice, and spread that over the avocado salsa.
Top with the cheese, cilantro and green onions and serve with the baked chips.
Nutrition information per serving: