Slice up an onion or two depending on how many people will be eating. I use sweet onions, but you can use white onions or even red onions.
Just before you put the onions in the melted butter, add a few dashes of Worcestershire sauce. You could also use Liquid Smoke or even soy sauce. Tailor it to your dish and your own taste. If you aren't using sweet onions but you want a sweet taste, add a teaspoon or two of sugar. Then throw your onions in.
Keep an eye on the pan and don't let it get too hot but you want the onions to cook. Stir them every couple minutes until they start to look like this:
From this point you can turn the heat down and let them sweat in the skillet until your meat dish is ready. Just before you serve your meat dish, throw a pile of these tender, sweet onions on top and you are guaranteed rave reviews!!