Heat the vegetable oil in a medium saucepan over medium heat. Add the red onion and garlic and cook, stirring occasionally, until the onion is soft, about 4 minutes. Add the chipotles, tomatoes and chicken broth and bring to a simmer over medium-high heat. Add the crushed chips and tequila; reduce the heat and simmer 10 minutes.
Transfer the soup to a blender and puree until smooth. Season with salt. Pour into small bowls (or shot glasses); top each with sour cream, cilantro and a whole chip.
When blending hot liquids, first let cool for 5 minutes or so, then transfer to a blender, filling only halfway. Put the lid on, leaving one corner open; Cover the lid with a kitchen towel to catch splatters and pulse until smooth.