The first thing to know about The Basement is context: an intimate, tightly controlled room in Edinburgh, United Kingdom, matched with the ambitions of a Mexican restaurant. Readers should look for flavor, texture and regional character, because that is where a restaurant of this type earns its reputation. It is most compelling for diners seeking flavor, texture and a point of view rooted in cuisine rather than decor alone, especially if the night calls for something more considered than a safe default.