Tyler Cowen has updated his Ethnic Dining Guide for the Washington DC area. Even if you don’t live in DC, the general remarks section is good advice to keep in mind when dining out.
The better ethnic restaurants tend to have many of their kind in a given geographic area. Single restaurant representations of a cuisine tend to disappoint. Competition increases quality and lowers prices. The presence of many restaurants of a kind in an area creates a pool of educated consumers, trained workers and chefs, and ingredient supplies - all manifestations of increasing returns to scale.
Cowen also wants against ordering ingredients-intensive dishes because of inferior American ingredients.
Avoid dishes that are “ingredients-intensive.” Raw ingredients in America - vegetables, butter, bread, meats, etc. - are below world standards. Even most underdeveloped countries have better raw ingredients than we do, at least if you have a U.S. income to spend there, and often even if one doesn’t. Ordering the plain steak in Latin America may be a great idea, but it is usually a mistake in Northern Virginia. Opt for dishes with sauces and complex mixes of ingredients. Go for dishes that are “composition-intensive.”