This is a real loosey-goosey recipe, especially for me. But the idea here is really that you can use whatever you've got on hand.
Step 1: Check the cupboard
I also had an onion and a shallot! (I later replanted the bottom of the shallot to grow a new one!)
You'll want some kind of oil to saute your onions
If you have vegetable stock or some such thing, awesome for you! You can just use water.
I was lucky enough to find a bouillon cube tucked away in the cupboard!
If you've got more stuff you want to add in - that celery wilting in the bottom drawer, some of those baby carrots in the back of the fridge - whatever you find, put it in there!
Step 2: Bacon!
I fried up a few pieces, and then used the grease from that to saute the onions instead of oil.
I really prefer to slowly saute onions over a low heat for a deeper, smoother flavor. If you want a real pungency from your onions, heat them quickly over high heat.
Step 3: Dump and heat
Cover and saute on LOW heat until your soup reaches the consistency you like. I prefer a stew that borders on a bowl of mushy beans :D
Salt and pepper to taste, and enjoy with some hearty bread for a great dinner on a cold night!