Preheat the oven to 400° F.In a large oven-safe skillet, heat the olive oil over high heat. Add the chicken and onion. Cook, breaking up the meat as it cooks until the chicken is browned, about 5 minutes. Add oregano and cumin, cook 1 minute. Stir in 2 cups enchilada sauce and the chipotle. Season with salt. Simmer 5 minutes. Remove from the heat and stir in the cilantro. Arrange the tortillas on top of the chicken. Pour over 1/2 cup enchilada sauce, then top with cheese. Bake 10-15 minutes, until the cheese is melted.To make the salsa. Combine everything in a bowl, season with salt. Serve the enchiladas warm, topped with avocado, Greek yogurt or sour cream, and plenty of salsa.