How about frying a big Spanish Onion, chipotle jalapenoes

Well it has sweet onions in it and as for the peppers I used 1 1/2 jalapenos this time. Some people dont like things hot so for here I have to make it wimpy. lol
I was trying to think of a way to use it when I go fishing this August.
Have any of you ever used the fire pit type cooking? Where you build your fire let it burn down to coals then place what you want to cook in the pit and cover it with sand?
If you know how to do this please let me know.
Thanks.