Rửa sạch vỉ nướng. Sau khi làm sạch, hãy phun một ít dầu lên vỉ nướng để chống dính. Quyết định sẽ sử dụng giấy bạc, rổ nướng, khay nướng hoặc xiên nướng. Nếu không có các dụng cụ trên, tốt nhất bạn hãy nướng hành tây cắt lát to hoặc nguyên củ. Quyết định sẽ phết nguyên liệu nào lên hành tây.

I'm interested in that, but I only have a few mins. Can you give me at most the first 500 characters of a detailed explanation in English about that?
Especially if you're going to put your onions directly on your grill, you need it to be clean. Even if you're not, a clean grill cooks better than a dirty one.  To clean your grill, put some vegetable oil on a paper towel, and wipe each rod down, one by one. You can also put the oil directly onto the grill and scrape off the grime with a grill spatula or other tool if necessary. Some grills have a "cleaning" setting. If the above isn't enough, you may wish to use this option if you have it. Oil