Preparing onions specifically for fajitas typically involves slicing them into strips suitable for sauting and incorporating into the dish. The goal is to create uniformly thin pieces that cook evenly and complement the other ingredients in texture and flavor. This method differs from dicing or mincing, focusing instead on strips that maintain some structural integrity during cooking.
Proper slicing contributes significantly to the overall fajita experience. Evenly cut pieces cook predictably, preventing some strips from burning while others remain undercooked. Consistent size also ensures a pleasing mouthfeel and aesthetic presentation within the finished dish. Historically, the practice of using sliced onions in fajitas likely stemmed from the influence of Northern Mexican cuisine, where grilling and sauting vegetables alongside meats are common.