Why is an onion passed over a hot grill before grilling?

You're likely thinking of caramelizing onions, which is a popular technique for adding sweetness and depth of flavor to grilled dishes. However, passing an onion over a hot grill before grilling isn't a common practice.

Here's why:

* It wouldn't caramelize the onion: Caramelizing onions requires slow, even cooking over low heat, typically in a pan with a bit of fat. Simply passing an onion over a hot grill wouldn't provide the time or heat distribution needed.

* It would likely burn the onion: A hot grill would quickly char the onion's surface, making it bitter and unpleasant.

Instead of passing an onion over the grill, you'd:

1. Slice the onion: Thinly slice the onion to ensure even cooking.

2. Caramelize in a pan: Heat a pan with a bit of oil over medium heat. Add the sliced onion and cook, stirring occasionally, until soft and golden brown. This process takes about 20-30 minutes.

3. Add to the grill: You can then add the caramelized onions to the grill, but it's not necessary. They'll provide a delicious base for your grilled dish without needing further cooking.

So, the next time you're looking to add sweetness to your grilled food, remember to caramelize your onions first!